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INTERNET STANDARD
Errata Exist

    Network Working Group                                      S. Hollenbeck
    Request for Comments: 5730                                VeriSign, Inc.
    STD: 69                                                      August 2009
    Obsoletes: 4930
    Category: Standards Track

                     Extensible Provisioning Protocol (EPP)

    Abstract

       This document describes an application-layer client-server protocol
       for the provisioning and management of objects stored in a shared
       central repository.  Specified in XML, the protocol defines generic
       object management operations and an extensible framework that maps
       protocol operations to objects.  This document includes a protocol
       specification, an object mapping template, and an XML media type
       registration.  This document obsoletes RFC 4930.

    Status of This Memo

       This document specifies an Internet standards track protocol for the
       Internet community, and requests discussion and suggestions for
       improvements.  Please refer to the current edition of the "Internet
       Official Protocol Standards" (STD 1) for the standardization state
       and status of this protocol.  Distribution of this memo is unlimited.

    Copyright Notice

       Copyright (c) 2009 IETF Trust and the persons identified as the
       document authors.  All rights reserved.

       This document is subject to BCP 78 and the IETF Trust's Legal
       Provisions Relating to IETF Documents in effect on the date of
       publication of this document (http://trustee.ietf.org/license-info).
       Please review these documents carefully, as they describe your rights
       and restrictions with respect to this document.

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    RFC 5730                          EPP                        August 2009

    Table of Contents

       1. Introduction ....................................................3
          1.1. Conventions Used in This Document ..........................3
       2. Protocol Description ............................................4
          2.1. Transport Mapping Considerations ...........................7
          2.2. Protocol Identification ....................................8
          2.3. Hello Format ...............................................8
          2.4. Greeting Format ............................................8
          2.5. Command Format ............................................12
          2.6. Response Format ...........................................13
          2.7. Protocol Extension Framework ..............................16
               2.7.1. Protocol Extension .................................16
               2.7.2. Object Extension ...................................17
               2.7.3. Command-Response Extension .........................18
          2.8. Object Identification .....................................18
          2.9. Protocol Commands .........................................19
               2.9.1. Session Management Commands ........................19
                      2.9.1.1. EPP <login> Command .......................20
                      2.9.1.2. EPP <logout> Command ......................22
               2.9.2. Query Commands .....................................23
                      2.9.2.1. EPP <check> Command .......................23
                      2.9.2.2. EPP <info> Command ........................25
                      2.9.2.3. EPP <poll> Command ........................26
                      2.9.2.4. EPP <transfer> Query Command ..............30
               2.9.3. Object Transform Commands ..........................31
                      2.9.3.1. EPP <create> Command ......................32
                      2.9.3.2. EPP <delete> Command ......................33
                      2.9.3.3. EPP <renew> Command .......................34
                      2.9.3.4. EPP <transfer> Command ....................35
                      2.9.3.5. EPP <update> Command ......................38
       3. Result Codes ...................................................39
       4. Formal Syntax ..................................................45
          4.1. Base Schema ...............................................45
          4.2. Shared Structure Schema ...................................56
       5. Internationalization Considerations ............................59
       6. IANA Considerations ............................................59
       7. Security Considerations ........................................60
       8. Acknowledgements ...............................................61
       9. References .....................................................62
          9.1. Normative References ......................................62
          9.2. Informative References ....................................62
       Appendix A.  Object Mapping Template ..............................64
       Appendix B.  Media Type Registration: application/epp+xml .........66
       Appendix C.  Changes from RFC 4930 ................................67

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    RFC 5730                          EPP                        August 2009

    1.  Introduction

       This document describes specifications for the Extensible
       Provisioning Protocol (EPP) version 1.0, an XML text protocol that
       permits multiple service providers to perform object-provisioning
       operations using a shared central object repository.  EPP is
       specified using the Extensible Markup Language (XML) 1.0 as described
       in [W3C.REC-xml-20040204] and XML Schema notation as described in
       [W3C.REC-xmlschema-1-20041028] and [W3C.REC-xmlschema-2-20041028].
       EPP meets and exceeds the requirements for a generic registry
       registrar protocol as described in [RFC3375].  This document
       obsoletes RFC 4930 [RFC4930].

       EPP content is identified by MIME media type application/epp+xml.
       Registration information for this media type is included in an
       appendix to this document.

       EPP is intended for use in diverse operating environments where
       transport and security requirements vary greatly.  It is unlikely
       that a single transport or security specification will meet the needs
       of all anticipated operators, so EPP was designed for use in a
       layered protocol environment.  Bindings to specific transport and
       security protocols are outside the scope of this specification.

       The original motivation for this protocol was to provide a standard
       Internet domain name registration protocol for use between domain
       name registrars and domain name registries.  This protocol provides a
       means of interaction between a registrar's applications and registry
       applications.  It is expected that this protocol will have additional
       uses beyond domain name registration.

       XML is case sensitive.  Unless stated otherwise, XML specifications
       and examples provided in this document MUST be interpreted in the
       character case presented to develop a conforming implementation.

    1.1.  Conventions Used in This Document

       The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
       "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
       document are to be interpreted as described in [RFC2119].

       In examples, "C:" represents lines sent by a protocol client and "S:"
       represents lines returned by a protocol server.  Indentation and
       white space in examples are provided only to illustrate element
       relationships and are not REQUIRED features of this protocol.  A
       protocol client that is authorized to manage an existing object is
       described as a "sponsoring" client throughout this document.

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    RFC 5730                          EPP                        August 2009

    2.  Protocol Description

       EPP is a stateful XML protocol that can be layered over multiple
       transport protocols.  Protected using lower-layer security protocols,
       clients exchange identification, authentication, and option
       information, and then engage in a series of client-initiated command-
       response exchanges.  All EPP commands are atomic (there is no partial
       success or partial failure) and designed so that they can be made
       idempotent (executing a command more than once has the same net
       effect on system state as successfully executing the command once).

       EPP provides four basic service elements: service discovery,
       commands, responses, and an extension framework that supports
       definition of managed objects and the relationship of protocol
       requests and responses to those objects.

       An EPP server MUST respond to client-initiated communication (which
       can be either a lower-layer connection request or an EPP service
       discovery message) by returning a greeting to a client.  A server
       MUST promptly respond to each EPP command with a coordinated response
       that describes the results of processing the command.  The following
       server state machine diagram illustrates the message exchange process
       in detail:

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    RFC 5730                          EPP                        August 2009

                  |
                  V
          +-----------------+                  +-----------------+
          |   Waiting for   |     Connected    |     Prepare     |
          |      Client     |----------------->|     Greeting    |
          +-----------------+    or <hello>    +-----------------+
             ^                                           |
             | Close Connection                     Send |
             |     or Idle                      Greeting |
          +-----------------+                            V
          |       End       |     Timeout      +-----------------+
          |     Session     |<-----------------|   Waiting for   |
          +-----------------+                  |      Client     |
             ^    ^    ^        Send +-------->|  Authentication |
             |    |    |    Response |         +-----------------+
             |    |    |     +--------------+            |
             |    |    |     | Prepare Fail |            | <login>
             |    |    +-----|   Response   |            | Received
             |    |    Send  +--------------+            V
             |    |    2501          ^         +-----------------+
             |    |   Response       |         |   Processing    |
             |    |                  +---------|     <login>     |
             |    |                  Auth Fail +-----------------+
             |    |       Timeout                         |
             |    +-------------------------------+       | Auth OK
             |                                    |       V
             |   +-----------------+  <hello>  +-----------------+
             |   |     Prepare     |<----------|   Waiting for   |
             |   |     Greeting    |---------->|   Command or    |
             |   +-----------------+   Send    |     <hello>     |
             | Send x5xx             Greeting  +-----------------+
             | Response  +-----------------+  Send    ^  |
             +-----------|     Prepare     | Response |  | Command
                         |     Response    |----------+  | Received
                         +-----------------+             V
                                    ^          +-----------------+
                            Command |          |   Processing    |
                          Processed +----------|     Command     |
                                               +-----------------+

       Figure 1: EPP Server State Machine

       EPP commands fall into three categories: session management commands,
       query commands, and object transform commands.  Session management
       commands are used to establish and end persistent sessions with an
       EPP server.  Query commands are used to perform read-only object
       information retrieval operations.  Transform commands are used to
       perform read-write object management operations.

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    RFC 5730                          EPP                        August 2009

       Commands are processed by a server in the order they are received
       from a client.  Though an immediate response confirming receipt and
       processing of the command is produced by the server, the protocol
       includes features that allow for offline review of transform commands
       before the requested action is actually completed.  In such
       situations, the response from the server MUST clearly note that the
       command has been received and processed but that the requested action
       is pending.  The state of the corresponding object MUST clearly
       reflect processing of the pending action.  The server MUST also
       notify the client when offline processing of the action has been
       completed.  Object mappings SHOULD describe standard formats for
       notices that describe completion of offline processing.

       EPP uses XML namespaces to provide an extensible object management
       framework and to identify schemas required for XML instance parsing
       and validation.  These namespaces and schema definitions are used to
       identify both the base protocol schema and the schemas for managed
       objects.  The XML namespace prefixes used in examples (such as the
       string "foo" in "xmlns:foo") are solely for illustrative purposes.  A
       conforming implementation MUST NOT require the use of these or any
       other specific namespace prefixes.

       All XML instances SHOULD begin with an <?xml?> declaration to
       identify the version of XML that is being used, optionally identify
       use of the character encoding used, and optionally provide a hint to
       an XML parser that an external schema file is needed to validate the
       XML instance.  Conformant XML parsers recognize both UTF-8 (defined
       in RFC 3629 [RFC3629]) and UTF-16 (defined in RFC 2781 [RFC2781]);
       per RFC 2277 [RFC2277], UTF-8 is the RECOMMENDED character encoding
       for use with EPP.

       Character encodings other than UTF-8 and UTF-16 are allowed by XML.
       UTF-8 is the default encoding assumed by XML in the absence of an
       "encoding" attribute or a byte order mark (BOM); thus, the "encoding"
       attribute in the XML declaration is OPTIONAL if UTF-8 encoding is
       used.  EPP clients and servers MUST accept a UTF-8 BOM if present,
       though emitting a UTF-8 BOM is NOT RECOMMENDED.

       Example XML declarations:

       <?xml version="1.0" encoding="UTF-8" standalone="no"?>

       <?xml version="1.0" standalone="no"?>

       <?xml version="1.0" encoding="UTF-8"?>

       <?xml version="1.0"?>

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    RFC 5730                          EPP                        August 2009

    2.1.  Transport Mapping Considerations

       As described previously, EPP can be layered over multiple transport
       protocols.  There are, however, a common set of considerations that
       MUST be addressed by any transport mapping defined for EPP.  These
       include:

       -  The transport mapping MUST preserve command order.

       -  The transport mapping MUST address the relationship between
          sessions and the client-server connection concept.

       -  The transport mapping MUST preserve the stateful nature of the
          protocol.

       -  The transport mapping MUST frame data units.

       -  The transport mapping MUST be onto a transport, such as TCP
          [RFC0793] or Stream Control Transmission Protocol (SCTP)
          [RFC4960], that provides congestion avoidance that follows RFC
          2914 [RFC2914]; or, if it maps onto a protocol such as SMTP
          [RFC5321] or Blocks Extensible Exchange Protocol (BEEP) [RFC3080],
          then the performance issues need to take into account issues of
          overload, server availability, and so forth.

       -  The transport mapping MUST ensure reliability.

       -  The transport mapping MUST explicitly allow or prohibit
          pipelining.

       Pipelining, also known as command streaming, is when a client sends
       multiple commands to a server without waiting for each corresponding
       response.  After sending the commands, the client waits for the
       responses to arrive in the order corresponding to the completed
       commands.  Performance gains can sometimes be realized with
       pipelining, especially with high-latency transports, but there are
       additional considerations associated with defining a transport
       mapping that supports pipelining:

       -  Commands MUST be processed independent of each other.

       -  Depending on the transport, pipelining MAY be possible in the form
          of sending a complete session in a well-defined "batch".

       -  The transport mapping MUST describe how an error in processing a
          command affects continued operation of the session.

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       A transport mapping MUST explain how all of these requirements are
       met, given the transport protocol being used to exchange data.

    2.2.  Protocol Identification

       All EPP XML instances MUST begin with an <epp> element.  This element
       identifies the start of an EPP protocol element and the namespace
       used within the protocol.  The <epp> start element and the associated
       </epp> ending element MUST be applied to all structures sent by both
       clients and servers.

       Example "start" and "end" EPP elements:

       <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       </epp>

    2.3.  Hello Format

       EPP MAY be carried over both connection-oriented and connection-less
       transport protocols.  An EPP client MAY request a <greeting> from an
       EPP server at any time between a successful <login> command and a
       <logout> command by sending a <hello> to a server.  Use of this
       element is essential in a connection-less environment where a server
       cannot return a <greeting> in response to a client-initiated
       connection.  An EPP <hello> MUST be an empty element with no child
       elements.

       Example <hello>:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <hello/>
       C:</epp>

    2.4.  Greeting Format

       An EPP server responds to a successful connection and <hello> element
       by returning a <greeting> element to the client.  An EPP greeting
       contains the following elements:

       -  An <svID> element that contains the name of the server.

       -  An <svDate> element that contains the server's current date and
          time in Universal Coordinated Time (UTC).

       -  An <svcMenu> element that identifies the services supported by the
          server, including:

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          o  One or more <version> elements that identify the protocol
             versions supported by the server.

          o  One or more <lang> elements that contain the identifiers of the
             text response languages known by the server.  Language
             identifiers MUST be structured as documented in [RFC4646].

          o  One or more <objURI> elements that contain namespace URIs
             representing the objects that the server is capable of
             managing.  A server MAY limit object management privileges on a
             per-client basis.

          o  An OPTIONAL <svcExtension> element that contains one or more
             <extURI> elements that contain namespace URIs representing
             object extensions supported by the server.

          o  A <dcp> (data collection policy) element that contains child
             elements used to describe the server's privacy policy for data
             collection and management.  Policy implications usually extend
             beyond the client-server relationship.  Both clients and
             servers can have relationships with other entities that need to
             know the server operator's data collection policy to make
             informed provisioning decisions.  Policy information MUST be
             disclosed to provisioning entities, though the method of
             disclosing policy data outside of direct protocol interaction
             is beyond the scope of this specification.  Child elements
             include the following:

             *  An <access> element that describes the access provided by
                the server to the client on behalf of the originating data
                source.  The <access> element MUST contain one of the
                following child elements:

                +  <all/>: Access is given to all identified data.

                +  <none/>: No access is provided to identified data.

                +  <null/>: Data is not persistent, so no access is
                   possible.

                +  <personal/>: Access is given to identified data relating
                   to individuals and organizational entities.

                +  <personalAndOther/>: Access is given to identified data
                   relating to individuals, organizational entities, and
                   other data of a non-personal nature.

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                +  <other/>: Access is given to other identified data of a
                   non-personal nature.

             *  One or more <statement> elements that describe data
                collection purposes, data recipients, and data retention.
                Each <statement> element MUST contain a <purpose> element, a
                <recipient> element, and a <retention> element.  The
                <purpose> element MUST contain one or more of the following
                child elements that describe the purposes for which data is
                collected:

                +  <admin/>: Administrative purposes.  Information can be
                   used for administrative and technical support of the
                   provisioning system.

                +  <contact/>: Contact for marketing purposes.  Information
                   can be used to contact individuals, through a
                   communications channel other than the protocol, for the
                   promotion of a product or service.

                +  <prov/>: Object-provisioning purposes.  Information can
                   be used to identify objects and inter-object
                   relationships.

                +  <other/>: Other purposes.  Information may be used in
                   other ways not captured by the above definitions.

             *  The <recipient> element MUST contain one or more of the
                following child elements that describes the recipients of
                collected data:

                +  <other/>: Other entities following unknown practices.

                +  <ours>: Server operator and/or entities acting as agents
                   or entities for whom the server operator is acting as an
                   agent.  An agent in this instance is defined as a third
                   party that processes data only on behalf of the service
                   provider for the completion of the stated purposes.  The
                   <ours> element contains an OPTIONAL <recDesc> element
                   that can be used to describe the recipient.

                +  <public/>: Public forums.

                +  <same/>: Other entities following server practices.

                +  <unrelated/>: Unrelated third parties.

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    RFC 5730                          EPP                        August 2009

             *  The <retention> element MUST contain one of the following
                child elements that describes data retention practices:

                +  <business/>: Data persists per business practices.

                +  <indefinite/>: Data persists indefinitely.

                +  <legal/>: Data persists per legal requirements.

                +  <none/>: Data is not persistent and is not retained for
                   more than a brief period of time necessary to make use of
                   it during the course of a single online interaction.

                +  <stated/>: Data persists to meet the stated purpose.

             *  An OPTIONAL <expiry> element that describes the lifetime of
                the policy.  The <expiry> element MUST contain one of the
                following child elements:

                +  <absolute/>: The policy is valid from the current date
                   and time until it expires on the specified date and time.

                +  <relative/>: The policy is valid from the current date
                   and time until the end of the specified duration.

       Data collection policy elements are based on work described in the
       World Wide Web Consortium's Platform for Privacy Preferences
       [W3C.REC-P3P-20020416] specification.

       Example greeting:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <greeting>
       S:    <svID>Example EPP server epp.example.com</svID>
       S:    <svDate>2000-06-08T22:00:00.0Z</svDate>
       S:    <svcMenu>
       S:      <version>1.0</version>
       S:      <lang>en</lang>
       S:      <lang>fr</lang>
       S:      <objURI>urn:ietf:params:xml:ns:obj1</objURI>
       S:      <objURI>urn:ietf:params:xml:ns:obj2</objURI>
       S:      <objURI>urn:ietf:params:xml:ns:obj3</objURI>
       S:      <svcExtension>
       S:        <extURI>http://custom/obj1ext-1.0</extURI>
       S:      </svcExtension>
       S:    </svcMenu>
       S:    <dcp>

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       S:      <access><all/></access>
       S:      <statement>
       S:        <purpose><admin/><prov/></purpose>
       S:        <recipient><ours/><public/></recipient>
       S:        <retention><stated/></retention>
       S:      </statement>
       S:    </dcp>
       S:  </greeting>
       S:</epp>

    2.5.  Command Format

       An EPP client interacts with an EPP server by sending a command to
       the server and receiving a response from the server.  In addition to
       the standard EPP elements, an EPP command contains the following
       elements:

       -  A command element whose tag corresponds to one of the valid EPP
          commands described in this document.  The command element MAY
          contain either protocol-specified or object-specified child
          elements.

       -  An OPTIONAL <extension> element that MAY be used for server-
          defined command extensions.

       -  An OPTIONAL <clTRID> (client transaction identifier) element that
          MAY be used to uniquely identify the command to the client.
          Clients are responsible for maintaining their own transaction
          identifier space to ensure uniqueness.

       Example command with object-specified child elements:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <info>
       C:      <obj:info xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <obj:name>example</obj:name>
       C:      </obj:info>
       C:    </info>
       C:    <clTRID>ABC-12345</clTRID>
       C:  </command>
       C:</epp>

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    2.6.  Response Format

       An EPP server responds to a client command by returning a response to
       the client.  EPP commands are atomic, so a command will either
       succeed completely or fail completely.  Success and failure results
       MUST NOT be mixed.  In addition to the standard EPP elements, an EPP
       response contains the following elements:

       -  One or more <result> elements that document the success or failure
          of command execution.  If the command was processed successfully,
          only one <result> element MUST be returned.  If the command was
          not processed successfully, multiple <result> elements MAY be
          returned to document failure conditions.  Each <result> element
          contains the following attribute and child elements:

          o  A "code" attribute whose value is a four-digit, decimal number
             that describes the success or failure of the command.

          o  A <msg> element containing a human-readable description of the
             response code.  The language of the response is identified via
             an OPTIONAL "lang" attribute.  If not specified, the default
             attribute value MUST be "en" (English).

          o  Zero or more OPTIONAL <value> elements that identify a client-
             provided element (including XML tag and value) or other
             information that caused a server error condition.

          o  Zero or more OPTIONAL <extValue> elements that can be used to
             provide additional error diagnostic information, including:

             *  A <value> element that identifies a client-provided element
                (including XML tag and value) that caused a server error
                condition.

             *  A <reason> element containing a human-readable message that
                describes the reason for the error.  The language of the
                response is identified via an OPTIONAL "lang" attribute.  If
                not specified, the default attribute value MUST be "en"
                (English).

       -  An OPTIONAL <msgQ> element that describes messages queued for
          client retrieval.  A <msgQ> element MUST NOT be present if there
          are no messages queued for client retrieval.  A <msgQ> element MAY
          be present in responses to EPP commands other than the <poll>
          command if messages are queued for retrieval.  A <msgQ> element
          MUST be present in responses to the EPP <poll> command if messages
          are queued for retrieval.  The <msgQ> element contains the
          following attributes:

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          o  A "count" attribute that describes the number of messages that
             exist in the queue.

          o  An "id" attribute used to uniquely identify the message at the
             head of the queue.

          The <msgQ> element contains the following OPTIONAL child elements
          that MUST be returned in response to a <poll> request command and
          MUST NOT be returned in response to any other command, including a
          <poll> acknowledgement:

          o  A <qDate> element that contains the date and time that the
             message was enqueued.

          o  A <msg> element containing a human-readable message.  The
             language of the response is identified via an OPTIONAL "lang"
             attribute.  If not specified, the default attribute value MUST
             be "en" (English).  This element MAY contain XML content for
             formatting purposes, but the XML content is not specified by
             the protocol and will thus not be processed for validity.

       -  An OPTIONAL <resData> (response data) element that contains child
          elements specific to the command and associated object.

       -  An OPTIONAL <extension> element that MAY be used for server-
          defined response extensions.

       -  A <trID> (transaction identifier) element containing the
          transaction identifier assigned by the server to the command for
          which the response is being returned.  The transaction identifier
          is formed using the <clTRID> associated with the command if
          supplied by the client and a <svTRID> (server transaction
          identifier) that is assigned by and unique to the server.

       Transaction identifiers provide command-response synchronization
       integrity.  They SHOULD be logged, retained, and protected to ensure
       that both the client and the server have consistent temporal and
       state-management records.

       Example response without <value> or <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg lang="en">Command completed successfully</msg>
       S:    </result>
       S:    <trID>

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       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       Example response with <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:creData xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:name>example</obj:name>
       S:      </obj:creData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       Example response with error value elements:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="2004">
       S:      <msg>Parameter value range error</msg>
       S:      <value xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:elem1>2525</obj:elem1>
       S:      </value>
       S:    </result>
       S:    <result code="2005">
       S:      <msg>Parameter value syntax error</msg>
       S:      <value xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:elem2>ex(ample</obj:elem2>
       S:      </value>
       S:      <extValue>
       S:        <value xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:          <obj:elem3>abc.ex(ample</obj:elem3>
       S:        </value>
       S:        <reason>Invalid character found.</reason>
       S:      </extValue>

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       S:    </result>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       Example response with notice of waiting server messages:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <msgQ count="5" id="12345"/>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       Command success or failure MUST NOT be assumed if no response is
       returned or if a returned response is malformed.  Protocol
       idempotency ensures the safety of retrying a command in cases of
       response-delivery failure.

    2.7.  Protocol Extension Framework

       EPP provides an extension framework that allows features to be added
       at the protocol, object, and command-response levels.

    2.7.1.  Protocol Extension

       The EPP extension framework allows for definition of new protocol
       elements identified using XML namespace notation with a reference to
       an XML schema that defines the namespace.  The <epp> element that
       identifies the beginning of a protocol instance includes multiple
       child element choices, one of which is an <extension> element whose
       children define the extension.  For example, a protocol extension
       element would be described in generic terms as follows:

       C:<epp>
       C:  <extension>
       C:    <!-- One or more extension elements. -->
       C:    <ext:foo xmlns:ext="urn:ietf:params:xml:ns:ext">

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       C:      <!-- One or more extension child elements. -->
       C:    </ext:foo>
       C:  </extension>
       C:</epp>

       This document does not define mappings for specific extensions.
       Extension specifications MUST be described in separate documents that
       define the objects and operations subject to the extension.

    2.7.2.  Object Extension

       EPP provides an extensible object management framework that defines
       the syntax and semantics of protocol operations applied to a managed
       object.  This framework pushes the definition of each protocol
       operation into the context of a specific object, providing the
       ability to add mappings for new objects without having to modify the
       base protocol.

       Protocol elements that contain data specific to objects are
       identified using XML namespace notation with a reference to an XML
       schema that defines the namespace.  The schema for EPP supports use
       of dynamic object schemas on a per-command and per-response basis.
       For example, the start of an object-specific command element would be
       described in generic terms as follows:

       C:<EPPCommandName>
       C:  <object:command xmlns:object="urn:ietf:params:xml:ns:object">
       C:    <!-- One or more object-specific command elements. -->
       C:  </object:command>
       C:</EPPCommandName>

       An object-specific response element would be described similarly:

       S:<resData>
       S:  <object:resData xmlns:object="urn:ietf:params:xml:ns:object">
       S:    <!-- One or more object-specific response elements. -->
       S:  </object:resData>
       S:</resData>

       This document does not define mappings for specific objects.  The
       mapping of EPP to an object MUST be described in separate documents
       that specifically address each command and response in the context of
       the object.  A suggested object mapping outline is included as an
       appendix to this document.

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    2.7.3.  Command-Response Extension

       EPP provides a facility for protocol command and response extensions.
       Protocol commands and responses MAY be extended by an <extension>
       element that contains additional elements whose syntax and semantics
       are not explicitly defined by EPP or an EPP object mapping.  This
       element is OPTIONAL.  Extensions are typically defined by agreement
       between client and server and MAY be used to extend EPP for unique
       operational needs.  A server-extended command element would be
       described in generic terms as follows:

       C:<command>
       C:  <!-- EPPCommandName can be "create", "update", etc. -->
       C:  <EPPCommandName>
       C:    <object:command xmlns:object="urn:ietf:params:xml:ns:object">
       C:      <!-- One or more object-specific command elements. -->
       C:    </object:command>
       C:  </EPPCommandName>
       C:  <extension>
       C:    <!-- One or more server-defined elements. -->
       C:  </extension>
       C:</command>

       A server-extended response element would be described similarly:

       S:<response>
       S:  <result code="1000">
       S:    <msg lang="en">Command completed successfully</msg>
       S:  </result>
       S:  <extension>
       S:    <!-- One or more server-defined elements. -->
       S:  </extension>
       S:  <trID>
       S:    <clTRID>ABC-12345</clTRID>
       S:    <svTRID>54321-XYZ</svTRID>
       S:  </trID>
       S:</response>

       This document does not define any specific server extensions.  The
       mapping of server extensions to EPP MUST be described in separate
       documents that specifically address extended commands and responses
       in the server's operational context.

    2.8.  Object Identification

       Some objects, such as name servers and contacts, can have utility in
       multiple repositories.  However, maintaining disjoint copies of
       object information in multiple repositories can lead to

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       inconsistencies that have adverse consequences for the Internet.  For
       example, changing the name of a name server in one repository but not
       in a second repository that refers to the server for domain name
       delegation can produce unexpected DNS query results.

       Globally unique identifiers can help facilitate object-information
       sharing between repositories.  A globally unique identifier MUST be
       assigned to every object when the object is created; the identifier
       MUST be returned to the client as part of any request to retrieve the
       detailed attributes of an object.  Specific identifier values are a
       matter of repository policy, but they SHOULD be constructed according
       to the following algorithm:

       a.  Divide the provisioning repository world into a number of object
           repository classes.

       b.  Each repository within a class is assigned an identifier that is
           maintained by IANA.

       c.  Each repository is responsible for assigning a unique local
           identifier for each object within the repository.

       d.  The globally unique identifier is a concatenation of the local
           identifier, followed by a hyphen ("-", ASCII value 0x002D),
           followed by the repository identifier.

    2.9.  Protocol Commands

       EPP provides commands to manage sessions, retrieve object
       information, and perform transformation operations on objects.  All
       EPP commands are atomic and designed so that they can be made
       idempotent, either succeeding completely or failing completely and
       producing predictable results in case of repeated executions.  This
       section describes each EPP command, including examples with
       representative server responses.

    2.9.1.  Session Management Commands

       EPP provides two commands for session management: <login> to
       establish a session with a server and <logout> to end a session with
       a server.  The <login> command establishes an ongoing server session
       that preserves client identity and authorization information during
       the duration of the session.

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    2.9.1.1.  EPP <login> Command

       The EPP <login> command is used to establish a session with an EPP
       server in response to a greeting issued by the server.  A <login>
       command MUST be sent to a server before any other EPP command to
       establish an ongoing session.  A server operator MAY limit the number
       of failed login attempts N, 1 <= N <= infinity, after which a login
       failure results in the connection to the server (if a connection
       exists) being closed.

       A client identifier and initial password MUST be created on the
       server before a client can successfully complete a <login> command.
       The client identifier and initial password MUST be delivered to the
       client using an out-of-band method that protects the identifier and
       password from inadvertent disclosure.

       In addition to the standard EPP command elements, the <login> command
       contains the following child elements:

       -  A <clID> element that contains the client identifier assigned to
          the client by the server.

       -  A <pw> element that contains the client's plain text password.
          The value of this element is case sensitive.

       -  An OPTIONAL <newPW> element that contains a new plain text
          password to be assigned to the client for use with subsequent
          <login> commands.  The value of this element is case sensitive.

       -  An <options> element that contains the following child elements:

          -  A <version> element that contains the protocol version to be
             used for the command or ongoing server session.

          -  A <lang> element that contains the text response language to be
             used for the command or ongoing server session commands.

          The values of the <version> and <lang> elements MUST exactly match
          one of the values presented in the EPP greeting.

       -  A <svcs> element that contains one or more <objURI> elements that
          contain namespace URIs representing the objects to be managed
          during the session.  The <svcs> element MAY contain an OPTIONAL
          <svcExtension> element that contains one or more <extURI> elements
          that identify object extensions to be used during the session.

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       The PLAIN Simple Authentication and Security Layer (SASL) mechanism
       presented in [RFC4616] describes a format for providing a user
       identifier, an authorization identifier, and a password as part of a
       single plain-text string.  The EPP authentication mechanism is
       similar, though EPP does not require a session-level authorization
       identifier and the user identifier and password are separated into
       distinct XML elements.  Additional identification and authorization
       schemes MUST be provided at other protocol layers to provide more
       robust security services.

       Example <login> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <login>
       C:      <clID>ClientX</clID>
       C:      <pw>foo-BAR2</pw>
       C:      <newPW>bar-FOO2</newPW>
       C:      <options>
       C:        <version>1.0</version>
       C:        <lang>en</lang>
       C:      </options>
       C:      <svcs>
       C:        <objURI>urn:ietf:params:xml:ns:obj1</objURI>
       C:        <objURI>urn:ietf:params:xml:ns:obj2</objURI>
       C:        <objURI>urn:ietf:params:xml:ns:obj3</objURI>
       C:        <svcExtension>
       C:          <extURI>http://custom/obj1ext-1.0</extURI>
       C:        </svcExtension>
       C:      </svcs>
       C:    </login>
       C:    <clTRID>ABC-12345</clTRID>
       C:  </command>
       C:</epp>

       When a <login> command has been processed successfully, a server MUST
       respond with an EPP response with no <resData> element.  If
       successful, the server will respond by creating and maintaining a new
       session that SHOULD be terminated by a future <logout> command.

       Example <login> response:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>

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       S:    </result>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <login> command is used to establish a session with an EPP
       server.  A <login> command MUST be rejected if received within the
       bounds of an existing session.  This command MUST be available to all
       clients.

    2.9.1.2.  EPP <logout> Command

       The EPP <logout> command is used to end a session with an EPP server.
       The <logout> command MUST be represented as an empty element with no
       child elements.

       A server MAY end a session due to client inactivity or excessive
       client-session longevity.  The parameters for determining excessive
       client inactivity or session longevity are a matter of server policy
       and are not specified by this protocol.

       Transport mappings MUST explicitly describe any connection-oriented
       processing that takes place after processing a <logout> command and
       ending a session.

       Example <logout> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <logout/>
       C:    <clTRID>ABC-12345</clTRID>
       C:  </command>
       C:</epp>

       When a <logout> command has been processed successfully, a server
       MUST respond with an EPP response with no <resData> element.  If
       successful, the server MUST also end the current session.

       Example <logout> response:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1500">

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       S:      <msg>Command completed successfully; ending session</msg>
       S:    </result>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <logout> command is used to end a session with an EPP server.
       A <logout> command MUST be rejected if the command has not been
       preceded by a successful <login> command.  This command MUST be
       available to all clients.

    2.9.2.  Query Commands

    2.9.2.1.  EPP <check> Command

       The EPP <check> command is used to determine if an object can be
       provisioned within a repository.  It provides a hint that allows a
       client to anticipate the success or failure of provisioning an object
       using the <create> command as object-provisioning requirements are
       ultimately a matter of server policy.

       The elements needed to identify an object are object-specific, so the
       child elements of the <check> command are specified using the EPP
       extension framework.  In addition to the standard EPP command
       elements, the <check> command contains the following child elements:

       -  An object-specific <obj:check> element that identifies the objects
          to be queried.  Multiple objects of the same type MAY be queried
          within a single <check> command.

       Example <check> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <check>
       C:      <obj:check xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <obj:name>example1</obj:name>
       C:        <obj:name>example2</obj:name>
       C:        <obj:name>example3</obj:name>
       C:      </obj:check>
       C:    </check>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

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       When a <check> command has been processed successfully, a server MUST
       respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace.  The child elements of
       the <resData> element are object-specific, though the EPP <resData>
       element MUST contain a child <obj:chkData> element that contains one
       or more <obj:cd> (check data) elements.  Each <obj:cd> element
       contains the following child elements:

       -  An object-specific element that identifies the queried object.
          This element MUST contain an "avail" attribute whose value
          indicates object availability (can it be provisioned or not) at
          the moment the <check> command was completed.  A value of "1" or
          "true" means that the object can be provisioned.  A value of "0"
          or "false" means that the object cannot be provisioned.

       -  An OPTIONAL <obj:reason> element that MAY be provided when an
          object cannot be provisioned.  If present, this element contains
          server-specific text to help explain why the object cannot be
          provisioned.  This text MUST be represented in the response
          language previously negotiated with the client; an OPTIONAL "lang"
          attribute MAY be present to identify the language if the
          negotiated value is something other than the default value of "en"
          (English).

       Example <check> response:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:chkData xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:cd>
       S:          <obj:name avail="1">example1</obj:name>
       S:        </obj:cd>
       S:        <obj:cd>
       S:          <obj:name avail="0">example2</obj:name>
       S:          <obj:reason>In use</obj:reason>
       S:        </obj:cd>
       S:        <obj:cd>
       S:          <obj:name avail="1">example3</obj:name>
       S:        </obj:cd>
       S:      </obj:chkData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>

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       S:      <svTRID>54322-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <check> command is used to determine if an object can be
       provisioned within a repository.  This action MUST be open to all
       authorized clients.

    2.9.2.2.  EPP <info> Command

       The EPP <info> command is used to retrieve information associated
       with an existing object.  The elements needed to identify an object
       and the type of information associated with an object are both
       object-specific, so the child elements of the <info> command are
       specified using the EPP extension framework.  In addition to the
       standard EPP command elements, the <info> command contains the
       following child elements:

       -  An object-specific <obj:info> element that identifies the object
          to be queried.

       Example <info> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <info>
       C:      <obj:info xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:info>
       C:    </info>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

       When an <info> command has been processed successfully, a server MUST
       respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace and the Repository
       Object IDentifier (ROID) that was assigned to the object when the
       object was created.  Other child elements of the <resData> element
       are object-specific.

       Example <info> response:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>

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       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:infData xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:roid>EXAMPLE1-REP</obj:roid>
       S:        <!-- Object-specific elements. -->
       S:      </obj:infData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <info> command is used to retrieve information associated
       with an existing object.  This action SHOULD be limited to authorized
       clients; restricting this action to the sponsoring client is
       RECOMMENDED.

    2.9.2.3.  EPP <poll> Command

       The EPP <poll> command is used to discover and retrieve service
       messages queued by a server for individual clients.  If the message
       queue is not empty, a successful response to a <poll> command MUST
       return the first message from the message queue.  Each response
       returned from the server includes a server-unique message identifier
       that MUST be provided to acknowledge receipt of the message, and a
       counter that indicates the number of messages in the queue.  After a
       message has been received by the client, the client MUST respond to
       the message with an explicit acknowledgement to confirm that the
       message has been received.  A server MUST dequeue the message and
       decrement the queue counter after receiving acknowledgement from the
       client, making the next message in the queue (if any) available for
       retrieval.

       Servers can occasionally perform actions on objects that are not in
       direct response to a client request, or an action taken by one client
       can indirectly involve a second client.  Examples of such actions
       include deletion upon expiration, automatic renewal upon expiration,
       and transfer coordination; other types of service information MAY be
       defined as a matter of server policy.  Service messages SHOULD be
       created for passive clients affected by an action on an object.
       Service messages MAY also be created for active clients that request
       an action on an object, though such messages MUST NOT replace the
       normal protocol response to the request.  For example, <transfer>
       actions SHOULD be reported to the client that has the authority to

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       approve or reject a transfer request.  Other methods of server-client
       action notification, such as offline reporting, are also possible and
       are beyond the scope of this specification.

       Message queues can consume server resources if clients do not
       retrieve and acknowledge messages on a regular basis.  Servers MAY
       implement other mechanisms to dequeue and deliver messages if queue
       maintenance needs exceed server resource consumption limits.  Server
       operators SHOULD consider time-sensitivity and resource management
       factors when selecting a delivery method for service information
       because some message types can be reasonably delivered using non-
       protocol methods that require fewer server resources.

       Some of the information returned in response to a <poll> command can
       be object-specific, so some child elements of the <poll> response MAY
       be specified using the EPP extension framework.  The <poll> command
       MUST be represented as an empty element with no child elements.  An
       "op" attribute with value "req" is REQUIRED to retrieve the first
       message from the server message queue.  An "op" attribute (with value
       "ack") and a "msgID" attribute (whose value corresponds to the value
       of the "id" attribute copied from the <msg> element in the message
       being acknowledged) are REQUIRED to acknowledge receipt of a message.

       Example <poll> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <poll op="req"/>
       C:    <clTRID>ABC-12345</clTRID>
       C:  </command>
       C:</epp>

       The returned result code notes that a message has been dequeued and
       returned in response to a <poll> command.

       Example <poll> response with object-specific information:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1301">
       S:      <msg>Command completed successfully; ack to dequeue</msg>
       S:    </result>
       S:    <msgQ count="5" id="12345">
       S:      <qDate>2000-06-08T22:00:00.0Z</qDate>
       S:      <msg>Transfer requested.</msg>
       S:    </msgQ>

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       S:    <resData>
       S:      <obj:trnData
       S:       xmlns:obj="urn:ietf:params:xml:ns:obj-1.0">
       S:        <obj:name>example.com</obj:name>
       S:        <obj:trStatus>pending</obj:trStatus>
       S:        <obj:reID>ClientX</obj:reID>
       S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
       S:        <obj:acID>ClientY</obj:acID>
       S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
       S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
       S:      </obj:trnData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       A client MUST acknowledge each response to dequeue the message and
       make subsequent messages available for retrieval.

       Example <poll> acknowledgement command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <poll op="ack" msgID="12345"/>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

       A <poll> acknowledgement response notes the ID of the message that
       has been acknowledged and the number of messages remaining in the
       queue.

       Example <poll> acknowledgement response:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <msgQ count="4" id="12345"/>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>

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       S:    </trID>
       S:  </response>
       S:</epp>

       Service messages can also be returned without object information.

       Example <poll> response with mixed message content and without
       object-specific information:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1301">
       S:      <msg>Command completed successfully; ack to dequeue</msg>
       S:    </result>
       S:    <msgQ count="4" id="12346">
       S:      <qDate>2000-06-08T22:10:00.0Z</qDate>
       S:      <msg lang="en">Credit balance low.
       S:        <limit>100</limit><bal>5</bal>
       S:      </msg>
       S:    </msgQ>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The returned result code and message is used to note an empty server
       message queue.

       Example <poll> response to note an empty message queue:

          S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
          S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
          S:  <response>
          S:    <result code="1300">
          S:      <msg>Command completed successfully; no messages</msg>
          S:    </result>
          S:    <trID>
          S:      <clTRID>ABC-12346</clTRID>
          S:      <svTRID>54321-XYZ</svTRID>
          S:    </trID>
          S:  </response>
          S:</epp>

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       The EPP <poll> command is used to discover and retrieve client
       service messages from a server.  This action SHOULD be limited to
       authorized clients; queuing service messages and limiting queue
       access on a per-client basis is RECOMMENDED.

    2.9.2.4.  EPP <transfer> Query Command

       The EPP <transfer> command provides a query operation that allows a
       client to determine real-time status of pending and completed
       transfer requests.  The elements needed to identify an object that is
       the subject of a transfer request are object-specific, so the child
       elements of the <transfer> query command are specified using the EPP
       extension framework.  In addition to the standard EPP command
       elements, the <transfer> command contains an "op" attribute with
       value "query" and the following child elements:

       -  An object-specific <obj:transfer> element that identifies the
          object whose transfer status is requested.

       Transfer status is typically considered sensitive information by the
       clients involved in the operation.  Object mappings MUST provide
       features to restrict transfer queries to authorized clients, such as
       by requiring authorization information as part of the request.

       Example <transfer> query command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <transfer op="query">
       C:      <obj:transfer xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:transfer>
       C:    </transfer>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

       When a <transfer> query command has been processed successfully, a
       server MUST respond with an EPP <resData> element that MUST contain a
       child element that identifies the object namespace.  The child
       elements of the <resData> element are object-specific, but they MUST
       include elements that identify the object, the status of the
       transfer, the identifier of the client that requested the transfer,
       the date and time that the request was made, the identifier of the
       client that is authorized to act on the request, the date and time by

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       which an action is expected, and an OPTIONAL date and time noting
       changes in the object's validity period (if applicable) that occur as
       a result of the transfer.

       Example <transfer> query response:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:trnData xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:name>example</obj:name>
       S:        <obj:trStatus>pending</obj:trStatus>
       S:        <obj:reID>ClientX</obj:reID>
       S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
       S:        <obj:acID>ClientY</obj:acID>
       S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
       S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
       S:      </obj:trnData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <transfer> command provides a query operation that allows a
       client to determine real-time status of pending and completed
       transfer requests.  This action SHOULD be limited to authorized
       clients; restricting queries to the requesting and responding clients
       is RECOMMENDED.  Object transfer MAY be unavailable or limited by
       object-specific policies.

    2.9.3.  Object Transform Commands

       EPP provides five commands to transform objects: <create> to create
       an instance of an object with a server, <delete> to remove an
       instance of an object from a server, <renew> to extend the validity
       period of an object, <transfer> to manage changes in client
       sponsorship of an object, and <update> to change information
       associated with an object.

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    2.9.3.1.  EPP <create> Command

       The EPP <create> command is used to create an instance of an object.
       An object can be created for an indefinite period of time, or an
       object can be created for a specific validity period.  The EPP
       mapping for an object MUST describe the status of an object with
       respect to time in order to include expected client and server
       behavior if a validity period is used.

       The elements needed to identify an object and associated attributes
       are object-specific, so the child elements of the <create> command
       are specified using the EPP extension framework.  In addition to the
       standard EPP command elements, the <create> command contains the
       following child elements:

       -  An object-specific <obj:create> element that identifies the object
          to be created and the elements that are required to create the
          object.

       Example <create> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <create>
       C:      <obj:create xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:create>
       C:    </create>
       C:    <clTRID>ABC-12345</clTRID>
       C:  </command>
       C:</epp>

       When a <create> command has been processed successfully, a server MAY
       respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace.  The child elements of
       the <resData> element are object-specific.

       Example <create> response with <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:creData xmlns:obj="urn:ietf:params:xml:ns:obj">

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       S:        <!-- Object-specific elements. -->
       S:      </obj:creData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12345</clTRID>
       S:      <svTRID>54321-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <create> command is used to create an instance of an object.
       This action SHOULD be limited to authorized clients and MAY be
       restricted on a per-client basis.

    2.9.3.2.  EPP <delete> Command

       The EPP <delete> command is used to remove an instance of an existing
       object.  The elements needed to identify an object are object-
       specific, so the child elements of the <delete> command are specified
       using the EPP extension framework.  In addition to the standard EPP
       command elements, the <delete> command contains the following child
       elements:

       -  An object-specific <obj:delete> element that identifies the object
          to be deleted.

       Example <delete> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <delete>
       C:      <obj:delete xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:delete>
       C:    </delete>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

       When a <delete> command has been processed successfully, a server MAY
       respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace.  The child elements of
       the <resData> element are object-specific.

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       Example <delete> response without <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <delete> command is used to remove an instance of an existing
       object.  This action SHOULD be limited to authorized clients;
       restricting this action to the sponsoring client is RECOMMENDED.

    2.9.3.3.  EPP <renew> Command

       The EPP <renew> command is used to extend the validity period of an
       existing object.  The elements needed to identify and extend the
       validity period of an object are object-specific, so the child
       elements of the <renew> command are specified using the EPP extension
       framework.  In addition to the standard EPP command elements, the
       <renew> command contains the following child elements:

       -  An object-specific <obj:renew> element that identifies the object
          to be renewed and the elements that are required to extend the
          validity period of the object.

       Example <renew> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <renew>
       C:      <obj:renew xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:renew>
       C:    </renew>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

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       When a <renew> command has been processed successfully, a server MAY
       respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace.  The child elements of
       the <resData> element are object-specific.

       Example <renew> response with <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:renData xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <!-- Object-specific elements. -->
       S:      </obj:renData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <renew> command is used to extend the validity period of an
       existing object.  This action SHOULD be limited to authorized
       clients; restricting this action to the sponsoring client is
       RECOMMENDED.  Object renewal MAY be unavailable or limited by object-
       specific policies.

    2.9.3.4.  EPP <transfer> Command

       The EPP <transfer> command is used to manage changes in client
       sponsorship of an existing object.  Clients can initiate a transfer
       request, cancel a transfer request, approve a transfer request, and
       reject a transfer request using the "op" command attribute.

       A client who wishes to assume sponsorship of a known object from
       another client uses the <transfer> command with the value of the "op"
       attribute set to "request".  Once a transfer has been requested, the
       same client can cancel the request using a <transfer> command with
       the value of the "op" attribute set to "cancel".  A request to cancel
       the transfer MUST be sent to the server before the current sponsoring
       client either approves or rejects the transfer request and before the
       server automatically processes the request due to responding client
       inactivity.

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       Once a transfer request has been received by the server, the server
       MUST notify the current sponsoring client of the requested transfer
       either by queuing a service message for retrieval via the <poll>
       command or by using an out-of-band mechanism to inform the client of
       the request.  The current status of a pending <transfer> command for
       any object can be found using the <transfer> query command.  Transfer
       service messages MUST include the object-specific elements specified
       for <transfer> command responses.

       The current sponsoring client MAY explicitly approve or reject the
       transfer request.  The client can approve the request using a
       <transfer> command with the value of the "op" attribute set to
       "approve".  The client can reject the request using a <transfer>
       command with the value of the "op" attribute set to "reject".

       A server MAY automatically approve or reject all transfer requests
       that are not explicitly approved or rejected by the current
       sponsoring client within a fixed amount of time.  The amount of time
       to wait for explicit action and the default server behavior are local
       matters not specified by EPP, but they SHOULD be documented in a
       server-specific profile document that describes default server
       behavior for client information.

       Objects eligible for transfer MUST have associated authorization
       information that MUST be provided to complete a <transfer> command.
       The type of authorization information required is object-specific;
       passwords or more complex mechanisms based on public key cryptography
       are typical.

       The elements needed to identify and complete the transfer of an
       object are object-specific, so the child elements of the <transfer>
       command are specified using the EPP extension framework.  In addition
       to the standard EPP command elements, the <transfer> command contains
       the following child elements:

       -  An object-specific <obj:transfer> element that identifies the
          object to be transferred and the elements that are required to
          process the transfer command.

       Example <transfer> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <transfer op="request">
       C:      <obj:transfer xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:transfer>

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       C:    </transfer>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

       When a <transfer> command has been processed successfully, a server
       MUST respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace.  The child elements of
       the <resData> element are object-specific, but they MUST include
       elements that identify the object, the status of the transfer, the
       identifier of the client that requested the transfer, the date and
       time that the request was made, the identifier of the client that is
       authorized to act on the request, the date and time by which an
       action is expected, and an OPTIONAL date and time noting changes in
       the object's validity period (if applicable) that occur as a result
       of the transfer.

       Example <transfer> response with <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1001">
       S:      <msg>Command completed successfully; action pending</msg>
       S:    </result>
       S:    <resData>
       S:      <obj:trnData xmlns:obj="urn:ietf:params:xml:ns:obj">
       S:        <obj:name>example</obj:name>
       S:        <obj:trStatus>pending</obj:trStatus>
       S:        <obj:reID>ClientX</obj:reID>
       S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
       S:        <obj:acID>ClientY</obj:acID>
       S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
       S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
       S:      </obj:trnData>
       S:    </resData>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>
       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <transfer> command is used to manage changes in client
       sponsorship of an existing object.  This action SHOULD be limited to
       authorized clients; restricting <transfer> requests to a client other
       than the current sponsoring client, <transfer> approval requests to

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       the current sponsoring client, and <transfer> cancellation requests
       to the original requesting client is RECOMMENDED.  Object transfer
       MAY be unavailable or limited by object-specific policies.

    2.9.3.5.  EPP <update> Command

       The EPP <update> command is used to change information associated
       with an existing object.  The elements needed to identify and modify
       an object are object-specific, so the child elements of the <update>
       command are specified using the EPP extension framework.  In addition
       to the standard EPP command elements, the <update> command contains
       the following child elements:

       -  An object-specific <obj:update> element that identifies the object
          to be updated and the elements that are required to modify the
          object.  Object-specific elements MUST identify values to be
          added, values to be removed, or values to be changed.

       Example <update> command:

       C:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       C:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       C:  <command>
       C:    <update>
       C:      <obj:update xmlns:obj="urn:ietf:params:xml:ns:obj">
       C:        <!-- Object-specific elements. -->
       C:      </obj:update>
       C:    </update>
       C:    <clTRID>ABC-12346</clTRID>
       C:  </command>
       C:</epp>

       When an <update> command has been processed successfully, a server
       MAY respond with an EPP <resData> element that MUST contain a child
       element that identifies the object namespace.  The child elements of
       the <resData> element are object-specific.

       Example <update> response without <resData>:

       S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
       S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
       S:  <response>
       S:    <result code="1000">
       S:      <msg>Command completed successfully</msg>
       S:    </result>
       S:    <trID>
       S:      <clTRID>ABC-12346</clTRID>
       S:      <svTRID>54322-XYZ</svTRID>

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       S:    </trID>
       S:  </response>
       S:</epp>

       The EPP <update> command is used to change information associated
       with an existing object.  This action SHOULD be limited to authorized
       clients; restricting this action to the sponsoring client is
       RECOMMENDED.

    3.  Result Codes

       EPP result codes are based on the theory of reply codes described in
       section 4.2.1 of [RFC5321].  EPP uses four decimal digits to describe
       the success or failure of each EPP command.  Each of the digits of
       the reply have special significance.

       The first digit denotes command success or failure.  The second digit
       denotes the response category, such as command syntax or security.
       The third and fourth digits provide explicit response detail within
       each response category.

       There are two values for the first digit of the reply code:

       1yzz    Positive completion reply.  The command was accepted and
               processed by the system without error.

       2yzz    Negative completion reply.  The command was not accepted, and
               the requested action did not occur.

       The second digit groups responses into one of six specific
       categories:

       x0zz    Protocol Syntax

       x1zz    Implementation-specific Rules

       x2zz    Security

       x3zz    Data Management

       x4zz    Server System

       x5zz    Connection Management

       The third and fourth digits provide response detail within the
       categories defined by the first and second digits.  The complete list
       of valid result codes is enumerated below and in the normative
       schema.

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       Every EPP response MUST include a result code and a human-readable
       description of the result code.  The language used to represent the
       description MAY be identified using an instance of the "lang"
       attribute within the <msg> element.  If not specified, the default
       language is English, identified as "en".  A description of the
       structure of valid values for the "lang" attribute is described in
       [RFC4646].

       Response text MAY be translated into other languages, though the
       translation MUST preserve the meaning of the code as described here.
       Response code values MUST NOT be changed when translating text.

       Response text in the table below is enclosed in quotes to clearly
       mark the beginning and ending of each response string.  Quotes MUST
       NOT be used to delimit these strings when returning response text via
       the protocol.

       Successful command completion responses:

          Code    Response text in English

          ____    ________________________

          1000    "Command completed successfully"

                  This is the usual response code for a successfully
                  completed command that is not addressed by any other
                  1xxx-series response code.

          1001    "Command completed successfully; action pending"

                  This response code MUST be returned when responding to a
                  command that requires offline activity before the
                  requested action can be completed.  See Section 2 for a
                  description of other processing requirements.

          1300    "Command completed successfully; no messages"

                  This response code MUST be returned when responding to a
                  <poll> request command and the server message queue is
                  empty.

          1301    "Command completed successfully; ack to dequeue"

                  This response code MUST be returned when responding to a
                  <poll> request command and a message has been retrieved
                  from the server message queue.

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          1500    "Command completed successfully; ending session"

                  This response code MUST be returned when responding to a
                  successful <logout> command.

       Command error responses:

          Code    Response text in English

          ____    ________________________

          2000    "Unknown command"

                  This response code MUST be returned when a server receives
                  a command element that is not defined by EPP.

          2001    "Command syntax error"

                  This response code MUST be returned when a server receives
                  an improperly formed command element.

          2002    "Command use error"

                  This response code MUST be returned when a server receives
                  a properly formed command element but the command cannot
                  be executed due to a sequencing or context error.  For
                  example, a <logout> command cannot be executed without
                  having first completed a <login> command.

          2003    "Required parameter missing"

                  This response code MUST be returned when a server receives
                  a command for which a required parameter value has not
                  been provided.

          2004    "Parameter value range error"

                  This response code MUST be returned when a server receives
                  a command parameter whose value is outside the range of
                  values specified by the protocol.  The error value SHOULD
                  be returned via a <value> element in the EPP response.

          2005    "Parameter value syntax error"

                  This response code MUST be returned when a server receives
                  a command containing a parameter whose value is improperly
                  formed.  The error value SHOULD be returned via a <value>
                  element in the EPP response.

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          2100    "Unimplemented protocol version"

                  This response code MUST be returned when a server receives
                  a command element specifying a protocol version that is
                  not implemented by the server.

          2101    "Unimplemented command"

                  This response code MUST be returned when a server receives
                  a valid EPP command element that is not implemented by the
                  server.  For example, a <transfer> command can be
                  unimplemented for certain object types.

          2102    "Unimplemented option"

                  This response code MUST be returned when a server receives
                  a valid EPP command element that contains a protocol
                  option that is not implemented by the server.

          2103    "Unimplemented extension"

                  This response code MUST be returned when a server receives
                  a valid EPP command element that contains a protocol
                  command extension that is not implemented by the server.

          2104    "Billing failure"

                  This response code MUST be returned when a server attempts
                  to execute a billable operation and the command cannot be
                  completed due to a client-billing failure.

          2105    "Object is not eligible for renewal"

                  This response code MUST be returned when a client attempts
                  to <renew> an object that is not eligible for renewal in
                  accordance with server policy.

          2106    "Object is not eligible for transfer"

                  This response code MUST be returned when a client attempts
                  to <transfer> an object that is not eligible for transfer
                  in accordance with server policy.

          2200    "Authentication error"

                  This response code MUST be returned when a server notes an
                  error when validating client credentials.

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          2201    "Authorization error"

                  This response code MUST be returned when a server notes a
                  client-authorization error when executing a command.  This
                  error is used to note that a client lacks privileges to
                  execute the requested command.

          2202    "Invalid authorization information"

                  This response code MUST be returned when a server receives
                  invalid command authorization information when attempting
                  to confirm authorization to execute a command.  This error
                  is used to note that a client has the privileges required
                  to execute the requested command, but the authorization
                  information provided by the client does not match the
                  authorization information archived by the server.

          2300    "Object pending transfer"

                  This response code MUST be returned when a server receives
                  a command to transfer of an object that is pending
                  transfer due to an earlier transfer request.

          2301    "Object not pending transfer"

                  This response code MUST be returned when a server receives
                  a command to confirm, reject, or cancel the transfer of an
                  object when no command has been made to transfer the
                  object.

          2302    "Object exists"

                  This response code MUST be returned when a server receives
                  a command to create an object that already exists in the
                  repository.

          2303    "Object does not exist"

                  This response code MUST be returned when a server receives
                  a command to query or transform an object that does not
                  exist in the repository.

          2304    "Object status prohibits operation"

                  This response code MUST be returned when a server receives
                  a command to transform an object that cannot be completed
                  due to server policy or business practices.  For example,
                  a server can disallow <transfer> commands under terms and

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                  conditions that are matters of local policy, or the server
                  might have received a <delete> command for an object whose
                  status prohibits deletion.

          2305    "Object association prohibits operation"

                  This response code MUST be returned when a server receives
                  a command to transform an object that cannot be completed
                  due to dependencies on other objects that are associated
                  with the target object.  For example, a server can
                  disallow <delete> commands while an object has active
                  associations with other objects.

          2306    "Parameter value policy error"

                  This response code MUST be returned when a server receives
                  a command containing a parameter value that is
                  syntactically valid but semantically invalid due to local
                  policy.  For example, the server can support a subset of a
                  range of valid protocol parameter values.  The error value
                  SHOULD be returned via a <value> element in the EPP
                  response.

          2307    "Unimplemented object service"

                  This response code MUST be returned when a server receives
                  a command to operate on an object service that is not
                  supported by the server.

          2308    "Data management policy violation"

                  This response code MUST be returned when a server receives
                  a command whose execution results in a violation of server
                  data management policies.  For example, removing all
                  attribute values or object associations from an object
                  might be a violation of a server's data management
                  policies.

          2400    "Command failed"

                  This response code MUST be returned when a server is
                  unable to execute a command due to an internal server
                  error that is not related to the protocol.  The failure
                  can be transient.  The server MUST keep any ongoing
                  session active.

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          2500    "Command failed; server closing connection"

                  This response code MUST be returned when a server receives
                  a command that cannot be completed due to an internal
                  server error that is not related to the protocol.  The
                  failure is not transient and will cause other commands to
                  fail as well.  The server MUST end the active session and
                  close the existing connection.

          2501    "Authentication error; server closing connection"

                  This response code MUST be returned when a server notes an
                  error when validating client credentials and a
                  server-defined limit on the number of allowable failures
                  has been exceeded.  The server MUST close the existing
                  connection.

          2502    "Session limit exceeded; server closing connection"

                  This response code MUST be returned when a server receives
                  a <login> command and the command cannot be completed
                  because the client has exceeded a system-defined limit on
                  the number of sessions that the client can establish.  It
                  might be possible to establish a session by ending
                  existing unused sessions and closing inactive connections.

    4.  Formal Syntax

       EPP is specified in XML Schema notation.  The formal syntax presented
       here is a complete schema representation of EPP suitable for
       automated validation of EPP XML instances.

       Two schemas are presented here.  The first schema is the base EPP
       schema.  The second schema defines elements and structures that can
       be used by both the base EPP schema and object mapping schema.  The
       BEGIN and END tags are not part of the schema; they are used to note
       the beginning and ending of the schema for URI registration purposes.

    4.1.  Base Schema

       Copyright (c) 2009 IETF Trust and the persons identified as authors
       of the code.  All rights reserved.

       Redistribution and use in source and binary forms, with or without
       modification, are permitted provided that the following conditions
       are met:

    Hollenbeck                  Standards Track                    [Page 45]

    RFC 5730                          EPP                        August 2009

       o  Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

       o  Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in
          the documentation and/or other materials provided with the
          distribution.

       o  Neither the name of Internet Society, IETF or IETF Trust, nor the
          names of specific contributors, may be used to endorse or promote
          products derived from this software without specific prior written
          permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
       "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
       LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
       A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
       OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
       LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

       BEGIN
       <?xml version="1.0" encoding="UTF-8"?>

       <schema targetNamespace="urn:ietf:params:xml:ns:epp-1.0"
               xmlns:epp="urn:ietf:params:xml:ns:epp-1.0"
               xmlns:eppcom="urn:ietf:params:xml:ns:eppcom-1.0"
               xmlns="http://www.w3.org/2001/XMLSchema"
               elementFormDefault="qualified">

       <!--
       Import common element types.
       -->
         <import namespace="urn:ietf:params:xml:ns:eppcom-1.0"/>

         <annotation>
           <documentation>
             Extensible Provisioning Protocol v1.0 schema.
           </documentation>
         </annotation>

       <!--
       Every EPP XML instance must begin with this element.
       -->

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    RFC 5730                          EPP                        August 2009

         <element name="epp" type="epp:eppType"/>

       <!--
       An EPP XML instance must contain a greeting, hello, command,
       response, or extension.
       -->
         <complexType name="eppType">
           <choice>
             <element name="greeting" type="epp:greetingType"/>
             <element name="hello"/>
             <element name="command" type="epp:commandType"/>
             <element name="response" type="epp:responseType"/>
             <element name="extension" type="epp:extAnyType"/>
           </choice>
         </complexType>

       <!--
       A greeting is sent by a server in response to a client connection
       or <hello>.
       -->
         <complexType name="greetingType">
           <sequence>
             <element name="svID" type="epp:sIDType"/>
             <element name="svDate" type="dateTime"/>
             <element name="svcMenu" type="epp:svcMenuType"/>
             <element name="dcp" type="epp:dcpType"/>
           </sequence>
         </complexType>

       <!--
       Server IDs are strings with minimum and maximum length restrictions.
       -->
         <simpleType name="sIDType">
           <restriction base="normalizedString">
             <minLength value="3"/>
             <maxLength value="64"/>
           </restriction>
         </simpleType>

       <!--
       A server greeting identifies available object services.
       -->
         <complexType name="svcMenuType">
           <sequence>
             <element name="version" type="epp:versionType"
              maxOccurs="unbounded"/>
             <element name="lang" type="language"
              maxOccurs="unbounded"/>

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    RFC 5730                          EPP                        August 2009

             <element name="objURI" type="anyURI"
              maxOccurs="unbounded"/>
             <element name="svcExtension" type="epp:extURIType"
              minOccurs="0"/>
           </sequence>
         </complexType>

       <!--
       Data Collection Policy types.
       -->
         <complexType name="dcpType">
           <sequence>
             <element name="access" type="epp:dcpAccessType"/>
             <element name="statement" type="epp:dcpStatementType"
              maxOccurs="unbounded"/>
             <element name="expiry" type="epp:dcpExpiryType"
              minOccurs="0"/>
           </sequence>
         </complexType>

         <complexType name="dcpAccessType">
           <choice>
             <element name="all"/>
             <element name="none"/>
             <element name="null"/>
             <element name="other"/>
             <element name="personal"/>
             <element name="personalAndOther"/>
           </choice>
         </complexType>

         <complexType name="dcpStatementType">
           <sequence>
             <element name="purpose" type="epp:dcpPurposeType"/>
             <element name="recipient" type="epp:dcpRecipientType"/>
             <element name="retention" type="epp:dcpRetentionType"/>
           </sequence>
         </complexType>

         <complexType name="dcpPurposeType">
           <sequence>
             <element name="admin"
              minOccurs="0"/>
             <element name="contact"
              minOccurs="0"/>
             <element name="other"
              minOccurs="0"/>
             <element name="prov"

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    RFC 5730                          EPP                        August 2009

              minOccurs="0"/>
           </sequence>
         </complexType>

         <complexType name="dcpRecipientType">
           <sequence>
             <element name="other"
              minOccurs="0"/>
             <element name="ours" type="epp:dcpOursType"
              minOccurs="0" maxOccurs="unbounded"/>
             <element name="public"
              minOccurs="0"/>
             <element name="same"
              minOccurs="0"/>
             <element name="unrelated"
              minOccurs="0"/>
           </sequence>
         </complexType>

         <complexType name="dcpOursType">
           <sequence>
             <element name="recDesc" type="epp:dcpRecDescType"
              minOccurs="0"/>
           </sequence>
         </complexType>

         <simpleType name="dcpRecDescType">
           <restriction base="token">
             <minLength value="1"/>
             <maxLength value="255"/>
           </restriction>
         </simpleType>

         <complexType name="dcpRetentionType">
           <choice>
             <element name="business"/>
             <element name="indefinite"/>
             <element name="legal"/>
             <element name="none"/>
             <element name="stated"/>
           </choice>
         </complexType>

         <complexType name="dcpExpiryType">
           <choice>
             <element name="absolute" type="dateTime"/>
             <element name="relative" type="duration"/>
           </choice>

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         </complexType>

       <!--
       Extension framework types.
       -->
         <complexType name="extAnyType">
           <sequence>
             <any namespace="##other"
              maxOccurs="unbounded"/>
           </sequence>
         </complexType>

         <complexType name="extURIType">
           <sequence>
             <element name="extURI" type="anyURI"
              maxOccurs="unbounded"/>
           </sequence>
         </complexType>

       <!--
       An EPP version number is a dotted pair of decimal numbers.
       -->
         <simpleType name="versionType">
           <restriction base="token">
             <pattern value="[1-9]+\.[0-9]+"/>
             <enumeration value="1.0"/>
           </restriction>
         </simpleType>

       <!--
       Command types.
       -->
         <complexType name="commandType">
           <sequence>
             <choice>
               <element name="check" type="epp:readWriteType"/>
               <element name="create" type="epp:readWriteType"/>
               <element name="delete" type="epp:readWriteType"/>
               <element name="info" type="epp:readWriteType"/>
               <element name="login" type="epp:loginType"/>
               <element name="logout"/>
               <element name="poll" type="epp:pollType"/>
               <element name="renew" type="epp:readWriteType"/>
               <element name="transfer" type="epp:transferType"/>
               <element name="update" type="epp:readWriteType"/>
             </choice>
             <element name="extension" type="epp:extAnyType"
              minOccurs="0"/>

    Hollenbeck                  Standards Track                    [Page 50]

    RFC 5730                          EPP                        August 2009

             <element name="clTRID" type="epp:trIDStringType"
              minOccurs="0"/>
           </sequence>
         </complexType>

       <!--
       The <login> command.
       -->
         <complexType name="loginType">
           <sequence>
             <element name="clID" type="eppcom:clIDType"/>
             <element name="pw" type="epp:pwType"/>
             <element name="newPW" type="epp:pwType"
              minOccurs="0"/>
             <element name="options" type="epp:credsOptionsType"/>
             <element name="svcs" type="epp:loginSvcType"/>
           </sequence>
         </complexType>

         <complexType name="credsOptionsType">
           <sequence>
             <element name="version" type="epp:versionType"/>
             <element name="lang" type="language"/>
           </sequence>
         </complexType>

         <simpleType name="pwType">
           <restriction base="token">
             <minLength value="6"/>
             <maxLength value="16"/>
           </restriction>
         </simpleType>

         <complexType name="loginSvcType">
           <sequence>
             <element name="objURI" type="anyURI"
              maxOccurs="unbounded"/>
             <element name="svcExtension" type="epp:extURIType"
              minOccurs="0"/>
           </sequence>
         </complexType>

       <!--
       The <poll> command.
       -->
         <complexType name="pollType">
           <attribute name="op" type="epp:pollOpType"
            use="required"/>

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    RFC 5730                          EPP                        August 2009

           <attribute name="msgID" type="token"/>
         </complexType>

         <simpleType name="pollOpType">
           <restriction base="token">
             <enumeration value="ack"/>
             <enumeration value="req"/>
           </restriction>
         </simpleType>

       <!--
       The <transfer> command.  This is object-specific, and uses attributes
       to identify the requested operation.
       -->
         <complexType name="transferType">
           <sequence>
             <any namespace="##other"/>
           </sequence>
           <attribute name="op" type="epp:transferOpType"
            use="required"/>
         </complexType>

         <simpleType name="transferOpType">
           <restriction base="token">
             <enumeration value="approve"/>
             <enumeration value="cancel"/>
             <enumeration value="query"/>
             <enumeration value="reject"/>
             <enumeration value="request"/>
           </restriction>
         </simpleType>

       <!--
       All other object-centric commands.  EPP doesn't specify the syntax or
       semantics of object-centric command elements.  The elements MUST be
       described in detail in another schema specific to the object.
       -->
         <complexType name="readWriteType">
           <sequence>
             <any namespace="##other"/>
           </sequence>
         </complexType>

         <complexType name="trIDType">
           <sequence>
             <element name="clTRID" type="epp:trIDStringType"
              minOccurs="0"/>
             <element name="svTRID" type="epp:trIDStringType"/>

    Hollenbeck                  Standards Track                    [Page 52]

    RFC 5730                          EPP                        August 2009

           </sequence>
         </complexType>

         <simpleType name="trIDStringType">
           <restriction base="token">
             <minLength value="3"/>
             <maxLength value="64"/>
           </restriction>
         </simpleType>

       <!--
       Response types.
       -->
         <complexType name="responseType">
           <sequence>
             <element name="result" type="epp:resultType"
              maxOccurs="unbounded"/>
             <element name="msgQ" type="epp:msgQType"
              minOccurs="0"/>

             <element name="resData" type="epp:extAnyType"
              minOccurs="0"/>
             <element name="extension" type="epp:extAnyType"
              minOccurs="0"/>
             <element name="trID" type="epp:trIDType"/>
           </sequence>
         </complexType>

         <complexType name="resultType">
           <sequence>
             <element name="msg" type="epp:msgType"/>
             <choice minOccurs="0" maxOccurs="unbounded">
               <element name="value" type="epp:errValueType"/>
               <element name="extValue" type="epp:extErrValueType"/>
             </choice>
           </sequence>
           <attribute name="code" type="epp:resultCodeType"
            use="required"/>
         </complexType>

         <complexType name="errValueType" mixed="true">
           <sequence>
             <any namespace="##any" processContents="skip"/>
           </sequence>
           <anyAttribute namespace="##any" processContents="skip"/>
         </complexType>

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         <complexType name="extErrValueType">
           <sequence>
             <element name="value" type="epp:errValueType"/>
             <element name="reason" type="epp:msgType"/>
           </sequence>
         </complexType>

         <complexType name="msgQType">
           <sequence>
             <element name="qDate" type="dateTime"
              minOccurs="0"/>
             <element name="msg" type="epp:mixedMsgType"
              minOccurs="0"/>
           </sequence>
           <attribute name="count" type="unsignedLong"
            use="required"/>
           <attribute name="id" type="eppcom:minTokenType"
            use="required"/>
         </complexType>

         <complexType name="mixedMsgType" mixed="true">
           <sequence>
             <any processContents="skip"
              minOccurs="0" maxOccurs="unbounded"/>
           </sequence>
           <attribute name="lang" type="language"
            default="en"/>
         </complexType>

       <!--
       Human-readable text may be expressed in languages other than English.
       -->
         <complexType name="msgType">
           <simpleContent>
             <extension base="normalizedString">
               <attribute name="lang" type="language"
                default="en"/>
             </extension>
           </simpleContent>
         </complexType>

       <!--
       EPP result codes.
       -->
         <simpleType name="resultCodeType">
           <restriction base="unsignedShort">
             <enumeration value="1000"/>
             <enumeration value="1001"/>

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    RFC 5730                          EPP                        August 2009

             <enumeration value="1300"/>
             <enumeration value="1301"/>
             <enumeration value="1500"/>
             <enumeration value="2000"/>
             <enumeration value="2001"/>
             <enumeration value="2002"/>
             <enumeration value="2003"/>
             <enumeration value="2004"/>
             <enumeration value="2005"/>
             <enumeration value="2100"/>
             <enumeration value="2101"/>
             <enumeration value="2102"/>
             <enumeration value="2103"/>
             <enumeration value="2104"/>
             <enumeration value="2105"/>
             <enumeration value="2106"/>
             <enumeration value="2200"/>
             <enumeration value="2201"/>
             <enumeration value="2202"/>
             <enumeration value="2300"/>
             <enumeration value="2301"/>
             <enumeration value="2302"/>
             <enumeration value="2303"/>
             <enumeration value="2304"/>
             <enumeration value="2305"/>
             <enumeration value="2306"/>
             <enumeration value="2307"/>
             <enumeration value="2308"/>
             <enumeration value="2400"/>
             <enumeration value="2500"/>
             <enumeration value="2501"/>
             <enumeration value="2502"/>
           </restriction>
         </simpleType>

       <!--
       End of schema.
       -->
       </schema>
       END

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    4.2.  Shared Structure Schema

       Copyright (c) 2009 IETF Trust and the persons identified as authors
       of the code.  All rights reserved.

       Redistribution and use in source and binary forms, with or without
       modification, are permitted provided that the following conditions
       are met:

       o  Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

       o  Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in
          the documentation and/or other materials provided with the
          distribution.

       o  Neither the name of Internet Society, IETF or IETF Trust, nor the
          names of specific contributors, may be used to endorse or promote
          products derived from this software without specific prior written
          permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
       "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
       LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
       A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
       OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
       LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

       BEGIN
       <?xml version="1.0" encoding="UTF-8"?>

       <schema targetNamespace="urn:ietf:params:xml:ns:eppcom-1.0"
               xmlns:eppcom="urn:ietf:params:xml:ns:eppcom-1.0"
               xmlns="http://www.w3.org/2001/XMLSchema"
               elementFormDefault="qualified">

         <annotation>
           <documentation>
             Extensible Provisioning Protocol v1.0
             shared structures schema.
           </documentation>
         </annotation>

    Hollenbeck                  Standards Track                    [Page 56]

    RFC 5730                          EPP                        August 2009

       <!--
       Object authorization information types.
       -->
         <complexType name="pwAuthInfoType">
           <simpleContent>
             <extension base="normalizedString">
               <attribute name="roid" type="eppcom:roidType"/>
             </extension>
           </simpleContent>
         </complexType>

         <complexType name="extAuthInfoType">
           <sequence>
             <any namespace="##other"/>
           </sequence>
         </complexType>

       <!--
       <check> response types.
       -->
         <complexType name="reasonType">
           <simpleContent>
             <extension base="eppcom:reasonBaseType">
               <attribute name="lang" type="language"/>
             </extension>
           </simpleContent>
         </complexType>

         <simpleType name="reasonBaseType">
           <restriction base="token">
             <minLength value="1"/>
             <maxLength value="32"/>
           </restriction>
         </simpleType>

       <!--
       Abstract client and object identifier type.
       -->
         <simpleType name="clIDType">
           <restriction base="token">
             <minLength value="3"/>
             <maxLength value="16"/>
           </restriction>
         </simpleType>

       <!--
       DNS label type.
       -->

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    RFC 5730                          EPP                        August 2009

         <simpleType name="labelType">
           <restriction base="token">
             <minLength value="1"/>
             <maxLength value="255"/>
           </restriction>
         </simpleType>

       <!--
       Non-empty token type.
       -->
         <simpleType name="minTokenType">
           <restriction base="token">
             <minLength value="1"/>
           </restriction>
         </simpleType>

       <!--
       Repository Object IDentifier type.
       -->
         <simpleType name="roidType">
           <restriction base="token">
             <pattern value="(\w|_){1,80}-\w{1,8}"/>
           </restriction>
         </simpleType>

       <!--
       Transfer status identifiers.
       -->

         <simpleType name="trStatusType">
           <restriction base="token">
             <enumeration value="clientApproved"/>
             <enumeration value="clientCancelled"/>
             <enumeration value="clientRejected"/>
             <enumeration value="pending"/>
             <enumeration value="serverApproved"/>
             <enumeration value="serverCancelled"/>
           </restriction>
         </simpleType>

       <!--
       End of schema.
       -->
       </schema>
       END

    Hollenbeck                  Standards Track                    [Page 58]

    RFC 5730                          EPP                        August 2009

    5.  Internationalization Considerations

       EPP is represented in XML, which provides native support for encoding
       information using the Unicode character set and its more compact
       representations including UTF-8.  Conformant XML processors recognize
       both UTF-8 and UTF-16.  Though XML includes provisions to identify
       and use other character encodings through use of an "encoding"
       attribute in an <?xml?> declaration, use of UTF-8 is RECOMMENDED in
       environments where parser-encoding-support incompatibility exists.

       EPP includes a provision for returning a human-readable message with
       every result code.  This document describes result codes in English,
       but the actual text returned with a result MAY be provided in a
       language negotiated when a session is established.  Languages other
       than English MUST be noted through specification of a "lang"
       attribute for each message.  Valid values for the "lang" attribute
       and "lang" negotiation elements are described in [RFC4646].

       All date-time values presented via EPP MUST be expressed in Universal
       Coordinated Time using the Gregorian calendar.  XML Schema allows use
       of time zone identifiers to indicate offsets from the zero meridian,
       but this option MUST NOT be used with EPP.  The extended date-time
       form using upper case "T" and "Z" characters defined in
       [W3C.REC-xmlschema-2-20041028] MUST be used to represent date-time
       values, as XML Schema does not support truncated date-time forms or
       lower case "T" and "Z" characters.

    6.  IANA Considerations

       This document uses URNs to describe XML namespaces and XML schemas
       conforming to a registry mechanism described in [RFC3688].  Four URI
       assignments have been registered by the IANA.

       Registration request for the EPP namespace:

          URI: urn:ietf:params:xml:ns:epp-1.0

          Registrant Contact: See the "Author's Address" section of this
          document.

          XML: None.  Namespace URIs do not represent an XML specification.

       Registration request for the EPP XML schema:

          URI: urn:ietf:params:xml:schema:epp-1.0

          Registrant Contact: See the "Author's Address" section of this
          document.

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          XML: See the "Base Schema" section of this document.

       Registration request for the EPP shared structure namespace:

          URI: urn:ietf:params:xml:ns:eppcom-1.0

          Registrant Contact: See the "Author's Address" section of this
          document.

          XML: None.  Namespace URIs do not represent an XML specification.

       Registration request for the EPP shared structure XML schema:

          URI: urn:ietf:params:xml:schema:eppcom-1.0

          Registrant Contact: See the "Author's Address" section of this
          document.

          XML: See the "Shared Structure Schema" section of this document.

       A MIME media type registration template is included in Appendix B.

    7.  Security Considerations

       EPP provides only simple client-authentication services.  A passive
       attack is sufficient to recover client identifiers and passwords,
       allowing trivial command forgery.  Protection against most common
       attacks and more robust security services MUST be provided by other
       protocol layers.  Specifically, EPP instances MUST be protected using
       a transport mechanism or application protocol that provides
       integrity, confidentiality, and mutual, strong client-server
       authentication.

       EPP uses a variant of the PLAIN SASL mechanism described in [RFC4616]
       to provide a simple application-layer authentication service that
       augments or supplements authentication and identification services
       that might be available at other protocol layers.  Where the PLAIN
       SASL mechanism specifies provision of an authorization identifier,
       authentication identifier, and password as a single string separated
       by ASCII NUL characters, EPP specifies use of a combined
       authorization and authentication identifier and a password provided
       as distinct XML elements.

       Repeated password guessing attempts can be discouraged by limiting
       the number of <login> attempts that can be attempted on an open
       connection.  A server MAY close an open connection if multiple
       <login> attempts are made with either an invalid client identifier,

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       an invalid password, or both an invalid client identifier and an
       invalid password.

       EPP uses authentication information associated with objects to
       confirm object-transfer authority.  Authentication information
       exchanged between EPP clients and third-party entities MUST be
       exchanged using a facility that provides privacy and integrity
       services to protect against unintended disclosure and modification
       while in transit.

       EPP instances SHOULD be protected using a transport mechanism or
       application protocol that provides anti-replay protection.  EPP
       provides some protection against replay attacks through command
       idempotency and client-initiated transaction identification.
       Consecutive command replays will not change the state of an object in
       any way.  There is, however, a chance of unintended or malicious
       consequence if a command is replayed after intervening commands have
       changed the object state and client identifiers are not used to
       detect replays.  For example, a replayed <create> command that
       follows a <delete> command might succeed without additional
       facilities to prevent or detect the replay.

       As described in Section 2, EPP includes features that allow for
       offline review of transform commands before the requested action is
       actually completed.  The server is required to notify the client when
       offline processing of the action has been completed.  Notifications
       can be sent using an out-of-band mechanism that is not protected by
       the mechanism used to provide EPP transport security.  Notifications
       sent without EPP's transport-security services should be protected
       using another mechanism that provides an appropriate level of
       protection for the notification.

    8.  Acknowledgements

       RFC 3730 is a product of the PROVREG working group, which suggested
       improvements and provided many invaluable comments.  The author
       wishes to acknowledge the efforts of WG chairs Edward Lewis and Jaap
       Akkerhuis for their process and editorial contributions.  RFC 4930
       and this document are individual submissions, based on the work done
       in RFC 3730.

       Specific suggestions that have been incorporated into this document
       were provided by Chris Bason, Eric Brunner-Williams, Jordyn Buchanan,
       Roger Castillo Cortazar, Dave Crocker, Ayesha Damaraju, Sheer
       El-Showk, Patrik Faltstrom, James Gould, John Immordino, Dan Kohn,
       Hong Liu, Klaus Malorny, Dan Manley, Michael Mealling, Patrick
       Mevzek, Andrew Newton, Budi Rahardjo, Asbjorn Steira, Rick Wesson,
       and Jay Westerdal.

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    9.  References

    9.1.  Normative References

       [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119, March 1997.

       [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and
                  Languages", BCP 18, RFC 2277, January 1998.

       [RFC2914]  Floyd, S., "Congestion Control Principles", BCP 41,
                  RFC 2914, September 2000.

       [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
                  10646", STD 63, RFC 3629, November 2003.

       [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
                  January 2004.

       [RFC4646]  Phillips, A. and M. Davis, "Tags for Identifying
                  Languages", BCP 47, RFC 4646, September 2006.

       [W3C.REC-xml-20040204]
                  Sperberg-McQueen, C., Maler, E., Yergeau, F., Paoli, J.,
                  and T. Bray, "Extensible Markup Language (XML) 1.0 (Third
                  Edition)", World Wide Web Consortium FirstEdition REC-xml-
                  20040204, February 2004,
                  <http://www.w3.org/TR/2004/REC-xml-20040204>.

       [W3C.REC-xmlschema-1-20041028]
                  Maloney, M., Thompson, H., Mendelsohn, N., and D. Beech,
                  "XML Schema Part 1: Structures Second Edition", World Wide
                  Web Consortium Recommendation REC-xmlschema-1-20041028,
                  October 2004,
                  <http://www.w3.org/TR/2004/REC-xmlschema-1-20041028>.

       [W3C.REC-xmlschema-2-20041028]
                  Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes
                  Second Edition", World Wide Web Consortium
                  Recommendation REC-xmlschema-2-20041028, October 2004,
                  <http://www.w3.org/TR/2004/REC-xmlschema-2-20041028>.

    9.2.  Informative References

       [RFC0793]  Postel, J., "Transmission Control Protocol", STD 7,
                  RFC 793, September 1981.

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       [RFC2781]  Hoffman, P. and F. Yergeau, "UTF-16, an encoding of ISO
                  10646", RFC 2781, February 2000.

       [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
                  Types", RFC 3023, January 2001.

       [RFC3080]  Rose, M., "The Blocks Extensible Exchange Protocol Core",
                  RFC 3080, March 2001.

       [RFC3375]  Hollenbeck, S., "Generic Registry-Registrar Protocol
                  Requirements", RFC 3375, September 2002.

       [RFC4616]  Zeilenga, K., "The PLAIN Simple Authentication and
                  Security Layer (SASL) Mechanism", RFC 4616, August 2006.

       [RFC4930]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
                  RFC 4930, May 2007.

       [RFC4960]  Stewart, R., "Stream Control Transmission Protocol",
                  RFC 4960, September 2007.

       [RFC5321]  Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
                  October 2008.

       [W3C.REC-P3P-20020416]
                  Marchiori, M., "The Platform for Privacy Preferences 1.0
                  (P3P1.0) Specification", World Wide Web Consortium
                  Recommendation REC-P3P-20020416, April 2002,
                  <http://www.w3.org/TR/2002/REC-P3P-20020416>.

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    Appendix A.  Object Mapping Template

       This appendix describes a recommended outline for documenting the EPP
       mapping of an object.  Documents that describe EPP object mappings
       SHOULD describe the mapping in a format similar to the one used here.
       Additional sections are required if the object mapping is written in
       Internet-Draft or RFC format.

       1. Introduction

          Provide an introduction that describes the object and gives an
          overview of the mapping to EPP.

       2. Object Attributes

          Describe the attributes associated with the object, including
          references to syntax specifications as appropriate.  Examples of
          object attributes include a name or identifier and dates
          associated with modification events.

       3. EPP Command Mapping

       3.1.  EPP Query Commands

       3.1.1.  EPP <check> Command

          Describe the object-specific mappings required to implement the
          EPP <check> command.  Include both sample commands and sample
          responses.

       3.1.2.  EPP <info> Command

          Describe the object-specific mappings required to implement the
          EPP <info> command.  Include both sample commands and sample
          responses.

       3.1.3.  EPP <poll> Command

          Describe the object-specific mappings required to implement the
          EPP <poll> command.  Include both sample commands and sample
          responses.

       3.1.4.  EPP <transfer> Command

          Describe the object-specific mappings required to implement the
          EPP <transfer> query command.  Include both sample commands and
          sample responses.

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       3.2.  EPP Transform Commands

       3.2.1.  EPP <create> Command

          Describe the object-specific mappings required to implement the
          EPP <create> command.  Include both sample commands and sample
          responses.  Describe the status of the object with respect to
          time, including expected client and server behavior if a validity
          period is used.

       3.2.2.  EPP <delete> Command

          Describe the object-specific mappings required to implement the
          EPP <delete> command.  Include both sample commands and sample
          responses.

       3.2.3.  EPP <renew> Command

          Describe the object-specific mappings required to implement the
          EPP <renew> command.  Include both sample commands and sample
          responses.

       3.2.4.  EPP <transfer> Command

          Describe the object-specific mappings required to implement the
          EPP <transfer> command.  Include both sample commands and sample
          responses.

       3.2.4.  EPP <update> Command

          Describe the object-specific mappings required to implement the
          EPP <update> command.  Include both sample commands and sample
          responses.

       4. Formal Syntax

          Provide the XML schema for the object mapping.  An XML DTD MUST
          NOT be used, as DTDs do not provide sufficient support for XML
          namespaces and strong data typing.

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    Appendix B.  Media Type Registration: application/epp+xml

       MIME media type name: application

       MIME subtype name: epp+xml

       Required parameters: none

       Optional parameters: Same as the charset parameter of application/xml
       as specified in [RFC3023].

       Encoding considerations: Same as the encoding considerations of
       application/xml as specified in [RFC3023].

       Security considerations: This type has all of the security
       considerations described in [RFC3023] plus the considerations
       specified in the Security Considerations section of this document.

       Interoperability considerations: XML has proven to be interoperable
       across WWW Distributed Authoring and Versioning (WebDAV) clients and
       servers, and for import and export from multiple XML authoring tools.
       For maximum interoperability, validating processors are recommended.
       Although non-validating processors can be more efficient, they are
       not required to handle all features of XML.  For further information,
       see Section 2.9, "Standalone Document Declaration", and Section 5,
       "Conformance", of [W3C.REC-xml-20040204].

       Published specification: This document.

       Applications that use this media type: EPP is device-, platform-, and
       vendor-neutral and is supported by multiple service providers.

       Additional information: If used, magic numbers, fragment identifiers,
       base URIs, and use of the BOM should be as specified in [RFC3023].

       Magic number(s): None.

       File extension(s): .xml

       Macintosh file type code(s): "TEXT"

       Person & email address for further information: See the "Author's
       Address" section of this document.

       Intended usage: COMMON

       Author/Change controller: IETF

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    Appendix C.  Changes from RFC 4930

       1.   Changed "This document obsoletes RFC 3730" to "This document
            obsoletes RFC 4930".

       2.   Replaced references to RFC 2595 with references to RFC 4616.

       3.   Replaced references to RFC 2821 with references to RFC 5321.

       4.   Replaced references to RFC 2960 with references to RFC 4960.

       5.   Replaced references to RFC 3066 with references to RFC 4646.

       6.   Replaced references to RFC 3730 with references to RFC 4930.

       7.   Added "A protocol client that is authorized to manage an
            existing object is described as a "sponsoring" client throughout
            this document" in Section 1.1.

       8.   Changed "This action MUST be open to all authorized clients" to
            "This command MUST be available to all clients" in the
            descriptions of the <login> and <logout> commands.

       9.   Changed "Specific result codes are listed in the table below" to
            "The complete list of valid result codes is enumerated below and
            in the normative schema" in Section 3.

       10.  Added new paragraph to Section 7 to give guidance on the need to
            protect offline transaction notices.

       11.  Added reference to Appendix B in the IANA Considerations
            section.

       12.  Added BSD license text to XML schema section.

    Author's Address

       Scott Hollenbeck
       VeriSign, Inc.
       21345 Ridgetop Circle
       Dulles, VA  20166-6503
       US

       EMail: shollenbeck@verisign.com

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