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    Registration Protocols Extensions                              R. Carney
    Internet-Draft                                              GoDaddy Inc.
    Intended status: Standards Track                                G. Brown
    Expires: November 2, 2019                           CentralNic Group plc
                                                                   J. Frakes
                                                                 May 1, 2019

     Registry Fee Extension for the Extensible Provisioning Protocol (EPP)
                         draft-ietf-regext-epp-fees-16

    Abstract

       Given the expansion of the DNS namespace, and the proliferation of
       novel business models, it is desirable to provide a method for
       Extensible Provisioning Protocol (EPP) clients to query EPP servers
       for the fees and credits and provide expected fees and credits for
       certain commands and objects.  This document describes an EPP
       extension mapping for registry fees.

    Status of This Memo

       This Internet-Draft is submitted in full conformance with the
       provisions of BCP 78 and BCP 79.

       Internet-Drafts are working documents of the Internet Engineering
       Task Force (IETF).  Note that other groups may also distribute
       working documents as Internet-Drafts.  The list of current Internet-
       Drafts is at https://datatracker.ietf.org/drafts/current/.

       Internet-Drafts are draft documents valid for a maximum of six months
       and may be updated, replaced, or obsoleted by other documents at any
       time.  It is inappropriate to use Internet-Drafts as reference
       material or to cite them other than as "work in progress."

       This Internet-Draft will expire on November 2, 2019.

    Copyright Notice

       Copyright (c) 2019 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
       (https://trustee.ietf.org/license-info) in effect on the date of
       publication of this document.  Please review these documents
       carefully, as they describe your rights and restrictions with respect
       to this document.  Code Components extracted from this document must

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       include Simplified BSD License text as described in Section 4.e of
       the Trust Legal Provisions and are provided without warranty as
       described in the Simplified BSD License.

    Table of Contents

       1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
         1.1.  Conventions Used in This Document . . . . . . . . . . . .   3
       2.  Migrating to Newer Versions of This Extension . . . . . . . .   4
       3.  Extension Elements  . . . . . . . . . . . . . . . . . . . . .   4
         3.1.  Client Commands . . . . . . . . . . . . . . . . . . . . .   4
         3.2.  Currency Codes  . . . . . . . . . . . . . . . . . . . . .   5
         3.3.  Validity Periods  . . . . . . . . . . . . . . . . . . . .   5
         3.4.  Fees and Credits  . . . . . . . . . . . . . . . . . . . .   6
           3.4.1.  Refunds . . . . . . . . . . . . . . . . . . . . . . .   7
           3.4.2.  Grace Periods . . . . . . . . . . . . . . . . . . . .   7
           3.4.3.  Correlation between Refundability and Grace Periods .   7
           3.4.4.  Applicability . . . . . . . . . . . . . . . . . . . .   7
         3.5.  Account Balance . . . . . . . . . . . . . . . . . . . . .   8
         3.6.  Credit Limit  . . . . . . . . . . . . . . . . . . . . . .   8
         3.7.  Classification of Objects . . . . . . . . . . . . . . . .   8
         3.8.  Phase and Subphase Attributes . . . . . . . . . . . . . .   9
         3.9.  Reason  . . . . . . . . . . . . . . . . . . . . . . . . .  10
       4.  Server Handling of Fee Information  . . . . . . . . . . . . .  11
       5.  EPP Command Mapping . . . . . . . . . . . . . . . . . . . . .  12
         5.1.  EPP Query Commands  . . . . . . . . . . . . . . . . . . .  12
           5.1.1.  EPP <check> Command . . . . . . . . . . . . . . . . .  12
           5.1.2.  EPP Transfer Query Command  . . . . . . . . . . . . .  16
         5.2.  EPP Transform Commands  . . . . . . . . . . . . . . . . .  18
           5.2.1.  EPP <create> Command  . . . . . . . . . . . . . . . .  18
           5.2.2.  EPP <delete> Command  . . . . . . . . . . . . . . . .  20
           5.2.3.  EPP <renew> Command . . . . . . . . . . . . . . . . .  21
           5.2.4.  EPP <transfer> Command  . . . . . . . . . . . . . . .  23
           5.2.5.  EPP <update> Command  . . . . . . . . . . . . . . . .  25
       6.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . .  27
         6.1.  Fee Extension Schema  . . . . . . . . . . . . . . . . . .  27
       7.  Security Considerations . . . . . . . . . . . . . . . . . . .  32
       8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  32
         8.1.  XML Namespace . . . . . . . . . . . . . . . . . . . . . .  32
         8.2.  EPP Extension Registry  . . . . . . . . . . . . . . . . .  33
       9.  Implementation Status . . . . . . . . . . . . . . . . . . . .  33
         9.1.  RegistryEngine EPP Service  . . . . . . . . . . . . . . .  34
       10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  34
       11. Change History  . . . . . . . . . . . . . . . . . . . . . . .  35
         11.1.  Change from 15 to 16 . . . . . . . . . . . . . . . . . .  35
         11.2.  Change from 14 to 15 . . . . . . . . . . . . . . . . . .  35
         11.3.  Change from 13 to 14 . . . . . . . . . . . . . . . . . .  35
         11.4.  Change from 12 to 13 . . . . . . . . . . . . . . . . . .  35

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         11.5.  Change from 11 to 12 . . . . . . . . . . . . . . . . . .  35
         11.6.  Change from 10 to 11 . . . . . . . . . . . . . . . . . .  35
         11.7.  Change from 09 to 10 . . . . . . . . . . . . . . . . . .  35
         11.8.  Change from 08 to 09 . . . . . . . . . . . . . . . . . .  36
         11.9.  Change from 07 to 08 . . . . . . . . . . . . . . . . . .  36
         11.10. Change from 06 to 07 . . . . . . . . . . . . . . . . . .  36
         11.11. Change from 05 to 06 . . . . . . . . . . . . . . . . . .  36
         11.12. Change from 04 to 05 . . . . . . . . . . . . . . . . . .  36
         11.13. Change from 03 to 04 . . . . . . . . . . . . . . . . . .  36
         11.14. Change from 02 to 03 . . . . . . . . . . . . . . . . . .  37
         11.15. Change from 01 to 02 . . . . . . . . . . . . . . . . . .  37
         11.16. Change from 00 to 01 . . . . . . . . . . . . . . . . . .  37
         11.17. Change from draft-brown-00 to draft-ietf-regext-fees-00   37
       12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  37
         12.1.  Normative References . . . . . . . . . . . . . . . . . .  37
         12.2.  Informative References . . . . . . . . . . . . . . . . .  38
       Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  38

    1.  Introduction

       Historically, domain name registries have applied a simple fee
       structure for billable transactions, namely a basic unit price
       applied to domain <create>, <renew>, <transfer> and RGP [RFC3915]
       restore commands.  Given the relatively small number of EPP servers
       to which EPP clients have been required to connect, it has generally
       been the case that client operators have been able to obtain details
       of these fees out-of-band by contacting the server operators.

       Given the expansion of the DNS namespace, and the proliferation of
       novel business models, it is desirable to provide a method for EPP
       clients to query EPP servers for the fees and credits associated with
       certain commands and specific objects.

       This document describes an extension mapping for version 1.0 of the
       Extensible Provisioning Protocol (EPP) [RFC5730].  This EPP mapping
       provides a mechanism by which EPP clients may query the fees and
       credits associated with various billable transactions, and obtain
       their current account balance.

    1.1.  Conventions Used in This Document

       The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
       "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
       "OPTIONAL" in this document are to be interpreted as described in BCP
       14 [RFC2119] [RFC8174] when, and only when, they appear in all
       capitals, as shown here.

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

       "fee" is used as an abbreviation for "urn:ietf:params:xml:ns:epp:fee-
       1.0".  The XML namespace prefix "fee" is used, but implementations
       MUST NOT depend on it and instead employ a proper namespace-aware XML
       parser and serializer to interpret and output the XML documents.

       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 a required feature of this protocol.

    2.  Migrating to Newer Versions of This Extension

       (Note to RFC Editor: remove this section before publication as an
       RFC.)

       Servers which implement this extension SHOULD provide a way for
       clients to progressively update their implementations when a new
       version of the extension is deployed.

       Servers SHOULD (for a temporary migration period) provide support for
       older versions of the extension in parallel to the newest version,
       and allow clients to select their preferred version via the
       <svcExtension> element of the <login> command.

       If a client requests multiple versions of the extension at login,
       then, when preparing responses to commands which do not include
       extension elements, the server SHOULD only include extension elements
       in the namespace of the newest version of the extension requested by
       the client.

       When preparing responses to commands which do include extension
       elements, the server SHOULD only include extension elements for the
       extension versions present in the command.

    3.  Extension Elements

    3.1.  Client Commands

       The <fee:command> element is used in the EPP <check> command to
       determine the fee that is applicable to the given command.

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       The use of the <fee:command> keys off the use of the "name" attribute
       to define which transform fees the client is requesting information
       about.  Here is the list of possible values for the "name" attribute:

       o  "create" indicating a <create> command as defined in [RFC5730];
       o  "delete" indicating a <delete> command as defined in [RFC5730];
       o  "renew" indicating a <renew> command as defined in [RFC5730];
       o  "update" indicating a <update> command as defined in [RFC5730];
       o  "transfer" indicating a <transfer> command as defined in
          [RFC5730];
       o  If the server supports the Registry Grace Period Mapping
          [RFC3915], then the server MUST also support the "restore" value
          as defined in [RFC3915];
       o  "custom" indicating a custom command that uses the "customName"
          attribute to define the custom operation.

       The <fee:command> element MAY have an OPTIONAL "phase" attribute
       specifying a launch phase as described in [RFC8334].  It may also
       contain an OPTIONAL "subphase" attribute identifying the custom or
       sub-phase as described in [RFC8334].

    3.2.  Currency Codes

       The <fee:currency> element is used to indicate which currency fees
       are charged in.  This value of this element MUST be a three-character
       currency code from [ISO4217].

       Note that ISO 4217 provides the special "XXX" code, which MAY be used
       if the server uses a non-currency based system for assessing fees,
       such as a system of credits.

       The use of <fee:currency> elements in client commands is OPTIONAL: if
       a <fee:currency> element is not present in a command, the server MUST
       determine the currency based on the server default currency or based
       on the client's account settings which are agreed to by the client
       and server via an out-of-band channel.  However, the <fee:currency>
       element MUST be present in responses.

       Servers SHOULD NOT perform a currency conversion if a client uses an
       incorrect currency code.  Servers SHOULD return a 2004 "Parameter
       value range" error instead.

    3.3.  Validity Periods

       When querying for fee information using the <check> command, the
       <fee:period> element is used to indicate the units to be added to the
       registration period of objects by the <create>, <renew> and

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       <transfer> commands.  This element is derived from the
       <domain:period> element described in [RFC5731].

       The <fee:period> element is OPTIONAL in <check> commands, if omitted,
       the server MUST determine the fee(s) using the server default period.
       The <fee:period> element MUST be present in <check> responses.

    3.4.  Fees and Credits

       Servers which implement this extension will include elements in
       responses which provide information about the fees and/or credits
       associated with a given billable transaction.

       The <fee:fee> and <fee:credit> elements are used to provide this
       information.  The presence of a <fee:fee> element in a response
       indicates a debit against the client's account balance; a
       <fee:credit> element indicates a credit.  A <fee:fee> element MUST
       have a non-negative value.  A <fee:credit> element MUST have a
       negative value.

       A server MAY respond with multiple <fee:fee> and <fee:credit>
       elements in the same response.  In such cases, the net fee or credit
       applicable to the transaction is the arithmetic sum of the values of
       each of the <fee:fee> and/or <fee:credit> elements.  This amount
       applies to the total additional validity period applied to the object
       (where applicable) rather than to any incremental unit.

       The following attributes are defined for the <fee:fee> element.
       These are described in detail below:

       description: an OPTIONAL attribute which provides a human-readable
       description of the fee.  Servers should provide documentation on the
       possible values of this attribute, and their meanings.  An OPTIONAL
       "lang" attribute MAY be present to identify the language of the
       returned text and has a default value of "en" (English).

       refundable: an OPTIONAL boolean attribute indicating whether the fee
       is refundable if the object is deleted.

       grace-period: an OPTIONAL attribute which provides the time period
       during which the fee is refundable.

       applied: an OPTIONAL attribute indicating when the fee will be
       deducted from the client's account.

       The <fee:credit> element can take a "description" attribute as
       described above.  An OPTIONAL "lang" attribute MAY be present to

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       identify the language of the returned text and has a default value of
       "en" (English).

    3.4.1.  Refunds

       <fee:fee> elements MAY have an OPTIONAL "refundable" attribute which
       takes a boolean value.  Fees may be refunded under certain
       circumstances, such as when a domain application is rejected (as
       described in [RFC8334]) or when an object is deleted during the
       relevant Grace Period (see below).

       If the "refundable" attribute is omitted, then clients SHOULD NOT
       make any assumption about the refundability of the fee.

    3.4.2.  Grace Periods

       [RFC3915] describes a system of "grace periods", which are time
       periods following a billable transaction during which, if an object
       is deleted, the client receives a refund.

       The "grace-period" attribute MAY be used to indicate the relevant
       grace period for a fee.  If a server implements the Registry Grace
       Period extension [RFC3915], it MUST specify the grace period for all
       relevant transactions.

       If the "grace-period" attribute is omitted, then clients SHOULD NOT
       make any assumption about the grace period of the fee.

    3.4.3.  Correlation between Refundability and Grace Periods

       If a <fee:fee> element has a "grace-period" attribute then it MUST
       also be refundable and the "refundable" attribute MUST be true.  If
       the "refundable" attribute of a <fee:fee> element is false then it
       MUST NOT have a "grace-period" attribute.

    3.4.4.  Applicability

       Fees may be applied immediately upon receipt of a command from a
       client, or may only be applied once an out-of-band process (such as
       the processing of applications at the end of a launch phase) has
       taken place.

       The "applied" attribute of the <fee:fee> element allows servers to
       indicate whether a fee will be applied immediately, or whether it
       will be applied at some point in the future.  This attribute takes
       two possible values: "immediate" or "delayed".

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    3.5.  Account Balance

       The <fee:balance> element is an OPTIONAL element which MAY be
       included in server responses to transform commands.  If present, it
       can be used by the client to determine the remaining credit at the
       server.

       Whether or not the <fee:balance> is included in responses is a matter
       of server policy.  However, if a server chooses to offer support for
       this element, it MUST be included in responses to all "transform" or
       billable commands (e.g. <create>, <renew>, <update>, <delete>,
       <transfer op="request">).

       The value of the <fee:balance> MAY be negative.  A negative balance
       indicates that the server has extended a line of credit to the client
       (see below).

       If a server includes a <fee:balance> element in response to transform
       commands, the value of the element MUST reflect the client's account
       balance after any fees or credits associated with that command have
       been applied.  If the "applied" attribute of the <fee:fee> element is
       "delayed", then the <fee:balance> MUST reflect the client's account
       balance without any fees or credits associated with that command.

    3.6.  Credit Limit

       As described above, if a server returns a response containing a
       <fee:balance> with a negative value, then the server has extended a
       line of credit to the client.  A server MAY also include a
       <fee:creditLimit> element in responses that indicates the maximum
       credit available to a client.  A server MAY reject certain
       transactions if the absolute value of the <fee:balance> is equal to
       or exceeds the value of the <fee:creditLimit> element.

       Whether or not the <fee:creditLimit> is included in responses is a
       matter of server policy.  However, if a server chooses to offer
       support for this element, it MUST be included in responses to all
       "transform" commands (e.g. <create>, <renew>, <update>, <delete>,
       <transfer op="request">).

    3.7.  Classification of Objects

       Objects may be assigned to a particular class, category, or tier,
       each of which has a particular fee or set of fees associated with it.
       The <fee:class> element, which MAY appear in <check> and transform
       responses, is used to indicate the classification of an object.

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       If a server makes use of this element, it should provide clients with
       a list of all the values that the element may take via an out-of-band
       channel.  Servers MUST NOT use values which do not appear on this
       list.

       Servers that make use of this element MUST use a <fee:class> element
       with the value "standard" for all objects that are subject to the
       standard or default fee.

    3.8.  Phase and Subphase Attributes

       The <fee:command> element has two attributes, phase and subphase,
       that provide additional information related to a specific launch
       phase as described in [RFC8334].  These attributes are used as
       filters that should refine the server processing.

       If the client <fee:command> contains a server supported combination
       of phase/subphase the server MUST return fee data (including the
       phase/subphase attribute(s)) for the specific combination.

       If the client <fee:command> contains no phase/subphase attributes and
       the server has only one active phase/subphase combination the server
       MUST return data (including the phase/subphase attribute(s)) of the
       currently active phase/subphase.

       If the client <fee:command> contains no phase/subphase attributes and
       the server has more than one active phase/subphase combination the
       server MUST respond with a 2003 "Required parameter missing" error.

       If the client <fee:command> contains no phase/subphase attributes and
       the server is currently in a "quiet period" (e.g. not accepting
       registrations or applications) the server MUST return data consistent
       with the default general availability phase (e.g. "open" or "claims")
       including the appropriate phase/subphase attribute(s).

       If the client <fee:command> contains a phase attribute with no
       subphase and the server has only one active subphase (or no subphase)
       of this phase, the server MUST return data (including the phase/
       subphase attribute(s)) of the provided phase and currently active
       subphase.

       If the client <fee:command> contains a phase attribute with no
       subphase and the server has more than one active subphase combination
       of this phase, the server MUST respond with a 2003 "Required
       parameter missing" error.

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       If the client <fee:command> contains a subphase with no phase
       attribute the server MUST respond with a 2003 "Required parameter
       missing" error.

       If the client <fee:command> contains a phase attribute not defined in
       [RFC8334] or not supported by server the server MUST respond with a
       2004 "Parameter value range" error.

       If the client <fee:command> contains a subphase attribute (or phase/
       subphase combination) not supported by server the server MUST respond
       with a 2004 "Parameter value range" error.

    3.9.  Reason

       The <fee:reason> element is used to provide server specific text in
       an effort to better explain why a <check> command did not complete as
       the client expected.  An OPTIONAL "lang" attribute MAY be present to
       identify the language of the returned text and has a default value of
       "en" (English).

       The <fee:reason> element can be used within the server response
       <fee:command> element or within the <fee:cd> element.

       If the server cannot calculate the relevant fees, because the object,
       command, currency, period, class or some combination is invalid per
       server policy, the server has two ways of handling error processing
       of <fee:command> element(s):

       1.  Fast-fail - The server, upon error identification, MAY stop
           processing <fee:command> elements and return to the client a
           <fee:cd> containing the <fee:objID> and a <fee:reason> element
           detailing the reason for failure.

           S: <fee:cd avail="0">
           S:   <fee:objID>example.xyz</fee:objID>
           S:   <fee:reason>Only 1 year registration periods are
           S:   valid.</fee:reason>
           S: </fee:cd>

       2.  Partial-fail - The server, upon error identification, MAY
           continue processing <fee:command> elements and return to the
           client a <fee:cd> containing successfully processed <fee:command>
           elements and failed <fee:command> elements.  All returned failed
           <fee:command> elements MUST have a <fee:reason> element detailing
           the reason for failure, and the server MAY additionally include a
           <fee:reason> element at the <fee:cd> level.

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           S: <fee:cd avail="0">
           S:   <fee:objID>example.xyz</fee:objID>
           S:   <fee:command name="create">
           S:     <fee:period unit="y">2</fee:period>
           S:     <fee:reason>Only 1 year registration periods are
           S:     valid.</fee:reason>
           S:   </fee:command>
           S: </fee:cd>

       In either failure scenario the server MUST set the <fee:cd> avail
       attribute to false (0) and the server MUST process all objects in the
       client request.

    4.  Server Handling of Fee Information

       Depending on server policy, a client MAY be required to include the
       extension elements described in this document for certain transform
       commands.  Servers must provide clear documentation to clients about
       the circumstances in which this extension must be used.

       The server MUST return avail="0" in its response to a <check> command
       for any object in the <check> command that does not include the
       <fee:check> extension for which the server would likewise fail a
       domain <create> command when no <fee> extension is provided for that
       same object.

       If a server receives a <check> command from a client, which results
       in no possible fee combination but where a fee is required, the
       server MUST set the "avail" attribute of the <fee:cd> element to
       false and provide a <fee:reason>.

       If a server receives a <check> command from a client, which results
       in an ambiguous result (i.e. multiple possible fee combinations) the
       server MUST reject the command with a 2003 "Required parameter
       missing" error.

       If a server receives a command from a client, which does not include
       the fee extension data elements required by the server for that
       command, then the server MUST respond with a 2003 "Required parameter
       missing" error.

       If the currency or total fee provided by the client is less than the
       server's own calculation of the fee for that command, then the server
       MUST reject the command with a 2004 "Parameter value range" error.

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    5.  EPP Command Mapping

       A detailed description of the EPP syntax and semantics can be found
       in [RFC5730].

    5.1.  EPP Query Commands

       This extension does not add any elements to the EPP <poll> or <info>
       commands or responses.

    5.1.1.  EPP <check> Command

       This extension defines a new command called the Fee Check Command
       that defines additional elements for the EPP <check> command to
       provide fee information along with the availability information of
       the EPP <check> command.

       The command MAY contain an <extension> element which MAY contain a
       <fee:check> element.  The <fee:check> element MAY contain one
       <fee:currency> element and MUST contain one or more <fee:command>
       elements.

       The <fee:command> element(s) contain(s) a "name" attribute (see
       Section 3.1), an OPTIONAL "phase" attribute, and an OPTIONAL
       "subphase" attribute (see Section 3.8).  The <fee:command> element(s)
       MAY have the following child elements:

       o  An OPTIONAL <fee:period> element (as described in Section 3.3).

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       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:       <domain:check
       C:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       C:         <domain:name>example.com</domain:name>
       C:         <domain:name>example.net</domain:name>
       C:         <domain:name>example.xyz</domain:name>
       C:       </domain:check>
       C:     </check>
       C:     <extension>
       C:       <fee:check xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       C:         <fee:currency>USD</fee:currency>
       C:         <fee:command name="create">
       C:           <fee:period unit="y">2</fee:period>
       C:         </fee:command>
       C:         <fee:command name="renew"/>
       C:         <fee:command name="transfer"/>
       C:         <fee:command name="restore"/>
       C:       </fee:check>
       C:     </extension>
       C:     <clTRID>ABC-12345</clTRID>
       C:   </command>
       C: </epp>

       When the server receives a <check> command that includes the
       extension elements described above, its response MUST contain an
       <extension> element, which MUST contain a child <fee:chkData>
       element.  The <fee:chkData> element MUST contain a <fee:currency>
       element and a <fee:cd> for each element referenced in the client
       <check> command.

       Each <fee:cd> element MUST contain the following child elements:

       o  A <fee:objID> element, which MUST match an element referenced in
          the client <check> command.
       o  An OPTIONAL <fee:class> element (as described in Section 3.7).
       o  A <fee:command> element matching each <fee:command> (unless the
          "avail" attribute of the <fee:cd> if false) that appeared in the
          corresponding <fee:check> of the client command.  This element MAY
          have the OPTIONAL "standard" attribute, with a default value of
          "0" (or "false"), which indicates whether the fee matches the fee
          of the "standard" classification (see section 3.7).  This element
          MAY have the OPTIONAL "phase" and "subphase" attributes, which

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          SHOULD match the same attributes in the corresponding
          <fee:command> element of the client command if sent by the client.

       The <fee:cd> element also has an OPTIONAL "avail" attribute which is
       a boolean.  If the value of this attribute evaluates to false, this
       indicates that the server cannot calculate the relevant fees, because
       the object, command, currency, period, class or some combination is
       invalid per server policy.  If "avail" is false then the <fee:cd> or
       the <fee:command> element MUST contain a <fee:reason> element (as
       described in Section 3.9) and the server MAY eliminate some or all of
       the <fee:command> element(s).

       The <fee:command> element(s) MAY have the following child elements:

       o  An OPTIONAL <fee:period> element (as described in Section 3.3),
          which contains the same unit that appeared in the <fee:period>
          element of the command.  If the value of the preceding
          <fee:command> element is "restore", this element MUST NOT be
          included, otherwise it MUST be included.  If no <fee:period>
          appeared in the client command (and the command is not "restore")
          then the server MUST return its default period value.
       o  Zero or more <fee:fee> elements (as described in Section 3.4).
       o  Zero or more <fee:credit> elements (as described in Section 3.4).
       o  An OPTIONAL <fee:reason> element (as described in Section 3.9).

       If the "avail" attribute of the <fee:cd> element is true and if no
       <fee:fee> elements are present in a <fee:command> element, this
       indicates that no fee will be assessed by the server for this
       command.

       If the "avail" attribute is true, then the <fee:command> element MUST
       NOT contain a <fee:reason> element.

       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:       <domain:chkData
       S:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       S:         <domain:cd>
       S:           <domain:name avail="1">example.com</domain:name>
       S:         </domain:cd>
       S:         <domain:cd>

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       S:           <domain:name avail="1">example.net</domain:name>
       S:         </domain:cd>
       S:         <domain:cd>
       S:           <domain:name avail="1">example.xyz</domain:name>
       S:         </domain:cd>
       S:       </domain:chkData>
       S:     </resData>
       S:     <extension>
       S:       <fee:chkData
       S:           xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:cd avail="1">
       S:           <fee:objID>example.com</fee:objID>
       S:           <fee:class>Premium</fee:class>
       S:           <fee:command name="create">
       S:             <fee:period unit="y">2</fee:period>
       S:             <fee:fee
       S:               description="Registration Fee"
       S:               refundable="1"
       S:               grace-period="P5D">10.00</fee:fee>
       S:           </fee:command>
       S:           <fee:command name="renew">
       S:             <fee:period unit="y">1</fee:period>
       S:             <fee:fee
       S:               description="Renewal Fee"
       S:               refundable="1"
       S:               grace-period="P5D">10.00</fee:fee>
       S:           </fee:command>
       S:           <fee:command name="transfer">
       S:             <fee:period unit="y">1</fee:period>
       S:             <fee:fee
       S:               description="Transfer Fee"
       S:               refundable="1"
       S:               grace-period="P5D">10.00</fee:fee>
       S:           </fee:command>
       S:           <fee:command name="restore">
       S:             <fee:fee
       S:               description="Redemption Fee">15.00</fee:fee>
       S:           </fee:command>
       S:         </fee:cd>
       S:         <fee:cd avail="1">
       S:           <fee:objID>example.net</fee:objID>
       S:           <fee:class>standard</fee:class>
       S:           <fee:command name="create" standard="1">
       S:             <fee:period unit="y">2</fee:period>
       S:             <fee:fee
       S:               description="Registration Fee"
       S:               refundable="1"

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       S:               grace-period="P5D">5.00</fee:fee>
       S:           </fee:command>
       S:           <fee:command name="renew" standard="1">
       S:             <fee:period unit="y">1</fee:period>
       S:             <fee:fee
       S:               description="Renewal Fee"
       S:               refundable="1"
       S:               grace-period="P5D">5.00</fee:fee>
       S:           </fee:command>
       S:           <fee:command name="transfer" standard="1">
       S:             <fee:period unit="y">1</fee:period>
       S:             <fee:fee
       S:               description="Transfer Fee"
       S:               refundable="1"
       S:               grace-period="P5D">5.00</fee:fee>
       S:           </fee:command>
       S:           <fee:command name="restore" standard="1">
       S:             <fee:fee
       S:               description="Redemption Fee">5.00</fee:fee>
       S:           </fee:command>
       S:         </fee:cd>
       S:         <fee:cd avail="0">
       S:           <fee:objID>example.xyz</fee:objID>
       S:           <fee:command name="create">
       S:             <fee:period unit="y">2</fee:period>
       S:             <fee:reason>Only 1 year registration periods are
       S:               valid.</fee:reason>
       S:           </fee:command>
       S:         </fee:cd>
       S:       </fee:chkData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54322-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    5.1.2.  EPP Transfer Query Command

       This extension does not add any elements to the EPP <transfer> query
       command, but does include elements in the response, when the
       extension is included in the <login> command service extensions.

       When the <transfer> query command has been processed successfully, if
       the client has included the extension in the <login> command service
       <svcExtension> element, and if the client is authorized by the server
       to view information about the transfer, then the server MAY include

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       in the <extension> section of the EPP response a <fee:trnData>
       element, which contains the following child elements:

       o  A <fee:currency> element (as described in Section 3.2).
       o  A <fee:period> element (as described in Section 3.3).
       o  Zero or more <fee:fee> elements (as described in Section 3.4)
          containing the fees that will be charged to the gaining client.
       o  Zero or more <fee:credit> elements (as described in Section 3.4)
          containing the credits that will be refunded to the losing client.

       Servers SHOULD omit <fee:credit> when returning a response to the
       gaining client, and omit <fee:fee> elements when returning a response
       to the losing client.

       If no <fee:trnData> element is included in the response, then no fee
       will be assessed by the server for the transfer.

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       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="1001">
       S:       <msg>Command completed successfully; action pending</msg>
       S:     </result>
       S:     <resData>
       S:       <domain:trnData
       S:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       S:         <domain:name>example.com</domain:name>
       S:         <domain:trStatus>pending</domain:trStatus>
       S:         <domain:reID>ClientX</domain:reID>
       S:         <domain:reDate>2000-06-08T22:00:00.0Z</domain:reDate>
       S:         <domain:acID>ClientY</domain:acID>
       S:         <domain:acDate>2000-06-13T22:00:00.0Z</domain:acDate>
       S:         <domain:exDate>2002-09-08T22:00:00.0Z</domain:exDate>
       S:       </domain:trnData>
       S:     </resData>
       S:     <extension>
       S:       <fee:trnData xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:period unit="y">1</fee:period>
       S:         <fee:fee>5.00</fee:fee>
       S:       </fee:trnData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54322-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    5.2.  EPP Transform Commands

    5.2.1.  EPP <create> Command

       This extension adds elements to both the EPP <create> command and
       response, when the extension is included in the <login> command
       service extensions.

       When submitting a <create> command to the server, the client MAY
       include in the <extension> element a <fee:create> element which
       includes the following child elements:

       o  An OPTIONAL <fee:currency> element (as described in Section 3.2);
       o  One or more <fee:fee> elements (as described in Section 3.4).

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       The server MUST fail the <create> command if the <fee:fee> provided
       by the client is less than the server fee.

       When the <create> command has been processed successfully, and the
       client included the extension in the <login> command service
       extensions, and a fee was assessed by the server for the transaction,
       the server MUST include in the <extension> section of the EPP
       response a <fee:creData> element, which contains the following child
       elements:

       o  A <fee:currency> element (as described in Section 3.2);
       o  Zero or more <fee:fee> elements (as described in Section 3.4);
       o  Zero or more <fee:credit> elements (as described in Section 3.4);
       o  An OPTIONAL <fee:balance> element (as described in Section 3.5);
       o  An OPTIONAL <fee:creditLimit> element (as described in
          Section 3.6).

       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:       <domain:create
       C:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       C:         <domain:name>example.com</domain:name>
       C:         <domain:period unit="y">2</domain:period>
       C:         <domain:ns>
       C:           <domain:hostObj>ns1.example.net</domain:hostObj>
       C:           <domain:hostObj>ns2.example.net</domain:hostObj>
       C:         </domain:ns>
       C:         <domain:registrant>jd1234</domain:registrant>
       C:         <domain:contact type="admin">sh8013</domain:contact>
       C:         <domain:contact type="tech">sh8013</domain:contact>
       C:         <domain:authInfo>
       C:           <domain:pw>2fooBAR</domain:pw>
       C:         </domain:authInfo>
       C:       </domain:create>
       C:     </create>
       C:     <extension>
       C:       <fee:create xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       C:         <fee:currency>USD</fee:currency>
       C:         <fee:fee>5.00</fee:fee>
       C:       </fee:create>
       C:     </extension>
       C:     <clTRID>ABC-12345</clTRID>
       C:   </command>
       C: </epp>

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       Example <create> 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:       <domain:creData
       S:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       S:         <domain:name>example.com</domain:name>
       S:         <domain:crDate>1999-04-03T22:00:00.0Z</domain:crDate>
       S:         <domain:exDate>2001-04-03T22:00:00.0Z</domain:exDate>
       S:       </domain:creData>
       S:     </resData>
       S:     <extension>
       S:       <fee:creData xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:fee
       S:           description="Registration Fee"
       S:           lang="en"
       S:           refundable="1"
       S:           grace-period="P5D">5.00</fee:fee>
       S:         <fee:balance>-5.00</fee:balance>
       S:         <fee:creditLimit>1000.00</fee:creditLimit>
       S:       </fee:creData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54321-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    5.2.2.  EPP <delete> Command

       This extension does not add any elements to the EPP <delete> command,
       but does include elements in the response, when the extension is
       included in the <login> command service extensions.

       When the <delete> command has been processed successfully, and the
       client included the extension in the <login> command service
       extensions, the server MAY include in the <extension> section of the
       EPP response a <fee:delData> element, which contains the following
       child elements:

       o  A <fee:currency> element (as described in Section 3.2);

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       o  Zero or more <fee:fee> elements (as described in Section 3.4);
       o  Zero or more <fee:credit> elements (as described in Section 3.4);
       o  An OPTIONAL <fee:balance> element (as described in Section 3.5);
       o  An OPTIONAL <fee:creditLimit> element (as described in
          Section 3.6).

       Example <delete> 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:     <extension>
       S:       <fee:delData
       S:         xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:credit
       S:           description="AGP Credit"
       S:           lang="en">-5.00</fee:credit>
       S:         <fee:balance>1005.00</fee:balance>
       S:       </fee:delData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54321-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    5.2.3.  EPP <renew> Command

       This extension adds elements to both the EPP <renew> command and
       response, when the extension is included in the <login> command
       service extensions.

       When submitting a <renew> command to the server, the client MAY
       include in the <extension> element a <fee:renew> element which
       includes the following child elements:

       o  An OPTIONAL <fee:currency> element (as described in Section 3.2);
       o  One or more <fee:fee> elements (as described in Section 3.4).

       When the <renew> command has been processed successfully, and the
       client included the extension in the <login> command service
       extensions, the server MAY include in the <extension> section of the

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       EPP response a <fee:renData> element, which contains the following
       child elements:

       o  A <fee:currency> element (as described in Section 3.2);
       o  Zero or more <fee:fee> elements (as described in Section 3.4);
       o  Zero or more <fee:credit> elements (as described in Section 3.4);
       o  An OPTIONAL <fee:balance> element (as described in Section 3.5);
       o  An OPTIONAL <fee:creditLimit> element (as described in
          Section 3.6).

       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:       <domain:renew
       C:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       C:         <domain:name>example.com</domain:name>
       C:         <domain:curExpDate>2000-04-03</domain:curExpDate>
       C:         <domain:period unit="y">5</domain:period>
       C:       </domain:renew>
       C:     </renew>
       C:     <extension>
       C:       <fee:renew xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       C:         <fee:currency>USD</fee:currency>
       C:         <fee:fee>5.00</fee:fee>
       C:       </fee:renew>
       C:     </extension>
       C:     <clTRID>ABC-12345</clTRID>
       C:   </command>
       C: </epp>

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       Example <renew> 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:       <domain:renData
       S:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       S:         <domain:name>example.com</domain:name>
       S:         <domain:exDate>2005-04-03T22:00:00.0Z</domain:exDate>
       S:       </domain:renData>
       S:     </resData>
       S:     <extension>
       S:       <fee:renData xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:fee
       S:           refundable="1"
       S:           grace-period="P5D">5.00</fee:fee>
       S:         <fee:balance>1000.00</fee:balance>
       S:       </fee:renData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54322-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    5.2.4.  EPP <transfer> Command

       This extension adds elements to both the EPP <transfer> command and
       response, when the value of the "op" attribute of the <transfer>
       command element is "request", and the extension is included in the
       <login> command service extensions.

       When submitting a <transfer> command to the server, the client MAY
       include in the <extension> element a <fee:transfer> element which
       includes the following child elements:

       o  An OPTIONAL <fee:currency> element (as described in Section 3.2);
       o  One or more <fee:fee> elements (as described in Section 3.4).

       When the <transfer> command has been processed successfully, and the
       client included the extension in the <login> command service
       extensions, the server MAY include in the <extension> section of the

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       EPP response a <fee:trnData> element, which contains the following
       child elements:

       o  A <fee:currency> element (as described in Section 3.2);
       o  Zero or more <fee:fee> elements (as described in Section 3.4);
       o  Zero or more <fee:credit> elements (as described in Section 3.4);
       o  An OPTIONAL <fee:balance> element (as described in Section 3.5);
       o  An OPTIONAL <fee:creditLimit> element (as described in
          Section 3.6).

       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:       <domain:transfer
      C:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
      C:         <domain:name>example.com</domain:name>
      C:         <domain:period unit="y">1</domain:period>
      C:         <domain:authInfo>
      C:           <domain:pw roid="JD1234-REP">2fooBAR</domain:pw>
      C:         </domain:authInfo>
      C:       </domain:transfer>
      C:     </transfer>
      C:     <extension>
      C:       <fee:transfer xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
      C:         <fee:currency>USD</fee:currency>
      C:         <fee:fee>5.00</fee:fee>
      C:       </fee:transfer>
      C:     </extension>
      C:     <clTRID>ABC-12345</clTRID>
      C:   </command>
      C: </epp>

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       Example <transfer> 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="1001">
       S:       <msg>Command completed successfully; action pending</msg>
       S:     </result>
       S:     <resData>
       S:       <domain:trnData
       S:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       S:         <domain:name>example.com</domain:name>
       S:         <domain:trStatus>pending</domain:trStatus>
       S:         <domain:reID>ClientX</domain:reID>
       S:         <domain:reDate>2000-06-08T22:00:00.0Z</domain:reDate>
       S:         <domain:acID>ClientY</domain:acID>
       S:         <domain:acDate>2000-06-13T22:00:00.0Z</domain:acDate>
       S:         <domain:exDate>2002-09-08T22:00:00.0Z</domain:exDate>
       S:       </domain:trnData>
       S:     </resData>
       S:     <extension>
       S:       <fee:trnData xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:fee
       S:           refundable="1"
       S:           grace-period="P5D">5.00</fee:fee>
       S:       </fee:trnData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54322-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    5.2.5.  EPP <update> Command

       This extension adds elements to both the EPP <update> command and
       response, when the extension is included in the <login> command
       service extensions.

       When submitting a <update> command to the server, the client MAY
       include in the <extension> element a <fee:update> element which
       includes the following child elements:

       o  An OPTIONAL <fee:currency> element (as described in Section 3.2);
       o  One or more <fee:fee> elements (as described in Section 3.4).

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       When the <update> command has been processed successfully, and the
       client included the extension in the <login> command service
       extensions, the server MAY include in the <extension> section of the
       EPP response a <fee:updData> element, which contains the following
       child elements:

       o  A <fee:currency> element (as described in Section 3.2);
       o  Zero or more <fee:fee> elements (as described in Section 3.4);
       o  Zero or more <fee:credit> elements (as described in Section 3.4);
       o  An OPTIONAL <fee:balance> element (as described in Section 3.5);
       o  An OPTIONAL <fee:creditLimit> element (as described in
          Section 3.6).

       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:       <domain:update
       C:         xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
       C:         <domain:name>example.com</domain:name>
       C:         <domain:chg>
       C:           <domain:registrant>sh8013</domain:registrant>
       C:         </domain:chg>
       C:       </domain:update>
       C:     </update>
       C:     <extension>
       C:       <fee:update xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       C:         <fee:currency>USD</fee:currency>
       C:         <fee:fee>5.00</fee:fee>
       C:       </fee:update>
       C:     </extension>
       C:     <clTRID>ABC-12345</clTRID>
       C:   </command>
       C: </epp>

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       Example <update> 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:     <extension>
       S:       <fee:updData xmlns:fee="urn:ietf:params:xml:ns:epp:fee-1.0">
       S:         <fee:currency>USD</fee:currency>
       S:         <fee:fee>5.00</fee:fee>
       S:       </fee:updData>
       S:     </extension>
       S:     <trID>
       S:       <clTRID>ABC-12345</clTRID>
       S:       <svTRID>54321-XYZ</svTRID>
       S:     </trID>
       S:   </response>
       S: </epp>

    6.  Formal Syntax

       One schema is presented here that is the EPP Fee Extension schema.

       The formal syntax presented here is a complete schema representation
       of the object mapping suitable for automated validation of EPP XML
       instances.  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.

    6.1.  Fee Extension Schema

       Copyright (c) 2018 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

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

        <import namespace="urn:ietf:params:xml:ns:eppcom-1.0" />
        <import namespace="urn:ietf:params:xml:ns:domain-1.0" />

        <annotation>
          <documentation>
            Extensible Provisioning Protocol v1.0 Fee Extension
          </documentation>
        </annotation>

        <!-- Child elements found in EPP commands and responses -->
        <element name="check" type="fee:checkType" />
        <element name="chkData" type="fee:chkDataType" />
        <element name="create" type="fee:transformCommandType" />
        <element name="creData" type="fee:transformResultType" />
        <element name="renew" type="fee:transformCommandType" />
        <element name="renData" type="fee:transformResultType" />
        <element name="transfer" type="fee:transformCommandType" />
        <element name="trnData" type="fee:transformResultType" />
        <element name="update" type="fee:transformCommandType" />
        <element name="updData" type="fee:transformResultType" />
        <element name="delData" type="fee:transformResultType" />

        <!-- client <check> command -->
        <complexType name="checkType">

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          <sequence>
            <element name="currency" type="fee:currencyType"
              minOccurs="0" />
            <element name="command" type="fee:commandType"
              minOccurs="1" maxOccurs="unbounded" />
          </sequence>
        </complexType>

        <complexType name="objectIdentifierType">
          <simpleContent>
            <extension base="eppcom:labelType">
              <attribute name="element"
              type="NMTOKEN" default="name" />
            </extension>
          </simpleContent>
        </complexType>

        <!-- server <check> result -->
        <complexType name="chkDataType">
          <sequence>
            <element name="currency" type="fee:currencyType" />
            <element name="cd" type="fee:objectCDType"
              maxOccurs="unbounded" />
          </sequence>
        </complexType>

        <complexType name="objectCDType">
          <sequence>
            <element name="objID" type="fee:objectIdentifierType" />
            <element name="class" type="token" minOccurs="0" />
            <element name="command" type="fee:commandDataType"
              minOccurs="0" maxOccurs="unbounded" />
            <element name="reason" type="fee:reasonType" minOccurs="0" />
          </sequence>
          <attribute name="avail" type="boolean" default="1" />
        </complexType>

        <!-- general transform (create, renew, update, transfer) command -->
        <complexType name="transformCommandType">
          <sequence>
            <element name="currency" type="fee:currencyType"
              minOccurs="0" />
            <element name="fee" type="fee:feeType"
              maxOccurs="unbounded" />
            <element name="credit" type="fee:creditType"
              minOccurs="0" maxOccurs="unbounded" />
          </sequence>
        </complexType>

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        <!-- general transform (create, renew, update) result -->
        <complexType name="transformResultType">
          <sequence>
            <element name="currency" type="fee:currencyType"
              minOccurs="0" />
            <element name="period" type="domain:periodType"
              minOccurs="0" />
            <element name="fee" type="fee:feeType"
              minOccurs="0" maxOccurs="unbounded" />
            <element name="credit" type="fee:creditType"
              minOccurs="0" maxOccurs="unbounded" />
            <element name="balance" type="fee:balanceType"
              minOccurs="0" />
            <element name="creditLimit" type="fee:creditLimitType"
              minOccurs="0" />
          </sequence>
        </complexType>

        <!-- common types -->
        <simpleType name="currencyType">
          <restriction base="string">
            <pattern value="[A-Z]{3}" />
          </restriction>
        </simpleType>

        <complexType name="commandType">
          <sequence>
            <element name="period" type="domain:periodType"
              minOccurs="0" maxOccurs="1" />
          </sequence>
          <attribute name="name" type="fee:commandEnum"/>
          <attribute name="customName" type="token"/>
          <attribute name="phase" type="token" />
          <attribute name="subphase" type="token" />
        </complexType>

        <complexType name="commandDataType">
          <complexContent>
            <extension base="fee:commandType">
              <sequence>
                <element name="fee" type="fee:feeType"
                  minOccurs="0" maxOccurs="unbounded" />
                <element name="credit" type="fee:creditType"
                  minOccurs="0" maxOccurs="unbounded" />
                <element name="reason" type="fee:reasonType"
                  minOccurs="0" />
              </sequence>
              <attribute name="standard" type="boolean" default="0" />

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            </extension>
          </complexContent>
        </complexType>

        <complexType name="reasonType">
          <simpleContent>
            <extension base="token">
              <attribute name="lang" type="language" default="en"/>
            </extension>
          </simpleContent>
        </complexType>

        <simpleType name="commandEnum">
          <restriction base="token">
            <enumeration value="create"/>
            <enumeration value="delete"/>
            <enumeration value="renew"/>
            <enumeration value="update"/>
            <enumeration value="transfer"/>
            <enumeration value="restore"/>
            <enumeration value="custom"/>
          </restriction>
        </simpleType>

        <simpleType name="nonNegativeDecimal">
          <restriction base="decimal">
            <minInclusive value="0" />
          </restriction>
        </simpleType>

        <simpleType name="negativeDecimal">
          <restriction base="decimal">
            <maxInclusive value="0" />
          </restriction>
        </simpleType>

        <complexType name="feeType">
          <simpleContent>
            <extension base="fee:nonNegativeDecimal">
              <attribute name="description"/>
              <attribute name="lang" type="language" default="en"/>
              <attribute name="refundable" type="boolean" />
              <attribute name="grace-period" type="duration" />
              <attribute name="applied">
                <simpleType>
                  <restriction base="token">
                    <enumeration value="immediate" />
                    <enumeration value="delayed" />

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                  </restriction>
                </simpleType>
              </attribute>
            </extension>
          </simpleContent>
        </complexType>

        <complexType name="creditType">
          <simpleContent>
            <extension base="fee:negativeDecimal">
              <attribute name="description"/>
              <attribute name="lang" type="language" default="en"/>
            </extension>
          </simpleContent>
        </complexType>

        <simpleType name="balanceType">
          <restriction base="decimal" />
        </simpleType>

        <simpleType name="creditLimitType">
          <restriction base="decimal" />
        </simpleType>

      </schema>
      END

    7.  Security Considerations

       The mapping extensions described in this document do not provide any
       security services beyond those described by EPP [RFC5730], the EPP
       domain name mapping [RFC5731], and protocol layers used by EPP.  The
       security considerations described in these other specifications apply
       to this specification as well.

    8.  IANA Considerations

    8.1.  XML Namespace

       This document uses URNs to describe XML namespaces and XML schemas
       conforming to a registry mechanism described in [RFC3688].

       Registration request for the fee namespace:

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

       Registrant Contact: IESG

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

       Registration request for the fee schema:

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

       Registrant Contact: IESG

       XML: See the "Formal Syntax" section of this document.

    8.2.  EPP Extension Registry

       The EPP extension described in this document should be registered by
       the IANA in the EPP Extension Registry described in [RFC7451].  The
       details of the registration are as follows:

       Name of Extension: Registry Fee Extension for the Extensible
       Provisioning Protocol (EPP)

       Document status: Standards Track

       Reference: (insert reference to RFC version of this document)

       Registrant Name and Email Address: IESG, <iesg@ietf.org>

       TLDs: Any

       IPR Disclosure: None

       Status: Active

       Notes: None

    9.  Implementation Status

       Note to RFC Editor: Please remove this section and the reference to
       [RFC7942] before publication.

       This section records the status of known implementations of the
       protocol defined by this specification at the time of posting of this
       Internet-Draft, and is based on a proposal described in [RFC7942].
       The description of implementations in this section is intended to
       assist the IETF in its decision processes in progressing drafts to
       RFCs.  Please note that the listing of any individual implementation
       here does not imply endorsement by the IETF.  Furthermore, no effort
       has been spent to verify the information presented here that was
       supplied by IETF contributors.  This is not intended as, and must not
       be construed to be, a catalog of available implementations or their

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       features.  Readers are advised to note that other implementations may
       exist.

       According to [RFC7942], "this will allow reviewers and working groups
       to assign due consideration to documents that have the benefit of
       running code, which may serve as evidence of valuable experimentation
       and feedback that have made the implemented protocols more mature.
       It is up to the individual working groups to use this information as
       they see fit".

    9.1.  RegistryEngine EPP Service

       Organization: CentralNic

       Name: RegistryEngine EPP Service

       Description: Generic high-volume EPP service for gTLDs, ccTLDs and
       SLDs

       Level of maturity: Deployed in CentralNic's production environment as
       well as two other gTLD registry systems, and two ccTLD registry
       systems.

       Coverage: All aspects of the protocol are implemented.

       Licensing: Proprietary In-House software

       Contact: epp@centralnic.com

       URL: https://www.centralnic.com

    10.  Acknowledgements

       The authors wish to thank the following persons for their feedback
       and suggestions:

       o  James Gould of Verisign Inc
       o  Luis Munoz of ISC
       o  Michael Young of Architelos
       o  Ben Levac and Jeff Eckhaus of Demand Media
       o  Seth Goldman of Google
       o  Klaus Malorny and Michael Bauland of Knipp
       o  Jody Kolker, Joe Snitker and Kevin Allendorf of Go Daddy
       o  Michael Holloway of Com Laude
       o  Santosh Kalsangrah of Impetus Infotech
       o  Alex Mayrhofer of Nic.at
       o  Thomas Corte of Knipp Medien und Kommunikation GmbH

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    11.  Change History

    11.1.  Change from 15 to 16

       Updated per AD review and list comments: several grammar corrections;
       clarification text added to section 3.4.3 and 3.5; and a schema
       update for consistency by providing a "lang" attribute to the
       <fee:fee> and <fee:credit> "description" attribute detailed in
       section 3.4.

    11.2.  Change from 14 to 15

       Updated schema, moving the "standard" attribute of the
       "commandDataType" inside the <extension> block.

    11.3.  Change from 13 to 14

       Moved RFC 7451 reference from Normative to Informative section.

    11.4.  Change from 12 to 13

       Updated XML namespace and schema registration to be "epp" scoped -
       global replace of XML namespace from urn:ietf:params:xml:ns:fee-1.0
       to urn:ietf:params:xml:ns:epp:fee-1.0 and the XML schema registration
       from urn:ietf:params:xml:schema:fee-1.0 to
       urn:ietf:params:xml:schema:epp:fee-1.0.

    11.5.  Change from 11 to 12

       Updated references to current version of documents and moved the
       "standard" attribute from the check command (commandType) to the
       check response (commandDataType).

    11.6.  Change from 10 to 11

       Updated document per Working Group Last Call comments.  Made minor
       textual changes throughout for enhanced clarity per WGLC comments.

    11.7.  Change from 09 to 10

       Updated document per Working Group Last Call comments.  Updated
       schema to version 1.0 in anticipation of standardization, no changes
       were made to the latest, 0.25, schema.  Made minor textual changes
       throughout for enhanced clarity per WGLC comments.

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    11.8.  Change from 08 to 09

       Updated scheme to version 0.25 to allow tighter checking on
       <fee:command> by splitting the client and server definitions, moved
       the class element from the command to the object level and added an
       optional standard attribute to the command element.  Also updated
       section 3.1 for clarity on name attribute; updated section 3.9 for
       clarity on uses of <fee:reason>; removed second paragraph in section
       5.2.1 as it was duplicative of second to last paragraph in 4.0; and
       updated section 5.1.1 to add section references.

    11.9.  Change from 07 to 08

       Updated section 3.8 and 5.1.1 to provide clarity on server processing
       and response of various scenarios (i.e. "quiet" period processing).

    11.10.  Change from 06 to 07

       Updated section 3.8 and 4.0 to provide clarity on server processing
       and response of various scenarios.

    11.11.  Change from 05 to 06

       Updated scheme to version 0.23 to allow the return of no
       <fee:command> element(s) if an error situation occurs.  Edited
       section 3.8 extensively after input from interim meeting and REGEXT
       F2F meeting at IETF-99.  Added normative reference for draft-ietf-
       eppext-launchphase.

    11.12.  Change from 04 to 05

       Updated scheme to version 0.21 to support the lang attribute for the
       reason element of the objectCDType and the commandType types as well
       as to add the update command to the commandEnum type.  Updated
       section 3.1 to include language for the custom command.  Added
       section 3.9 to provide a description of the <fee:reason> element.
       Fixed typos and added clarification text on when client fee is less
       than server fee in section 4.  Additionally, I added description
       pointers to appropriate Section 3 definitions for element clarity
       throughout the document.

    11.13.  Change from 03 to 04

       Updated scheme to version 0.19 to correct typos and to replace the
       commandTypeValue type with the commandEnum type and customName
       attribute for stricter validation.  Updated various text for grammar
       and clarity.  Added text to section 4 clarifying the <check> response

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       when the client provided no fee extension but the server was
       expecting the extension.

    11.14.  Change from 02 to 03

       Updated scheme to version 0.17 to simplify the check command syntax.
       Moved fee avail to objectCDType to allow fast failing on error
       situations.  Removed the objectCheckType as it was no longer being
       used.  Updated examples to reflect these scheme changes.  Added
       language for server failing a <create> if the <fee:fee> passed by the
       client is less than the server fee.

    11.15.  Change from 01 to 02

       Updated scheme to version 0.15 to fix errors in CommandType,
       objectCDType, transformCommandType and transformResultType
       definitions.

    11.16.  Change from 00 to 01

       Added Roger Carney as author to finish draft.  Moved Formal Syntax
       section to main level numbering.  Various grammar, typos, and
       administrative edits for clarity.  Removed default value for the
       "applied" attribute of <fee:fee> so that it can truly be optional.
       Added support for the <delete> command to return a <fee:fee> element
       as well.  Modified default response on the <check> command for the
       optional <fee:period> when it was not provided in the command,
       leaving it to the server to provide the default period value.
       Extensive edits were done to the <check> command, the <check>
       response and to the fee extension schema (checkType, objectCheckType,
       objectIdentifierType, objectCDType, commandType) to support
       requesting and returning multiple transformation fees in a single
       call.  Added section on Phase/Subphase to provide more context on the
       uses.

    11.17.  Change from draft-brown-00 to draft-ietf-regext-fees-00

       Updated to be REGEXT WG document.

    12.  References

    12.1.  Normative References

       [ISO4217]  International Organization for Standardization, "Codes for
                  the representation of currencies", August 2015,
                  <https://www.iso.org/standard/64758.html>.

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       [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels", BCP 14, RFC 2119,
                  DOI 10.17487/RFC2119, March 1997,
                  <https://www.rfc-editor.org/info/rfc2119>.

       [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
                  DOI 10.17487/RFC3688, January 2004,
                  <https://www.rfc-editor.org/info/rfc3688>.

       [RFC3915]  Hollenbeck, S., "Domain Registry Grace Period Mapping for
                  the Extensible Provisioning Protocol (EPP)", RFC 3915,
                  DOI 10.17487/RFC3915, September 2004,
                  <https://www.rfc-editor.org/info/rfc3915>.

       [RFC5730]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
                  STD 69, RFC 5730, DOI 10.17487/RFC5730, August 2009,
                  <https://www.rfc-editor.org/info/rfc5730>.

       [RFC5731]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)
                  Domain Name Mapping", STD 69, RFC 5731,
                  DOI 10.17487/RFC5731, August 2009,
                  <https://www.rfc-editor.org/info/rfc5731>.

       [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
                  Code: The Implementation Status Section", BCP 205,
                  RFC 7942, DOI 10.17487/RFC7942, July 2016,
                  <https://www.rfc-editor.org/info/rfc7942>.

       [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
                  2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
                  May 2017, <https://www.rfc-editor.org/info/rfc8174>.

       [RFC8334]  Gould, J., Tan, W., and G. Brown, "Launch Phase Mapping
                  for the Extensible Provisioning Protocol (EPP)", RFC 8334,
                  DOI 10.17487/RFC8334, March 2018,
                  <https://www.rfc-editor.org/info/rfc8334>.

    12.2.  Informative References

       [RFC7451]  Hollenbeck, S., "Extension Registry for the Extensible
                  Provisioning Protocol", RFC 7451, DOI 10.17487/RFC7451,
                  February 2015, <https://www.rfc-editor.org/info/rfc7451>.

    Authors' Addresses

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       Roger Carney
       GoDaddy Inc.
       14455 N. Hayden Rd. #219
       Scottsdale, AZ  85260
       US

       Email: rcarney@godaddy.com
       URI:   http://www.godaddy.com

       Gavin Brown
       CentralNic Group plc
       35-39 Moorgate
       London, England  EC2R 6AR
       GB

       Phone: +44 20 33 88 0600
       Email: gavin.brown@centralnic.com
       URI:   http://www.centralnic.com

       Jothan Frakes

       Email: jothan@jothan.com
       URI:   http://jothan.com

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