Extensible Provisioning Protocol (EPP) Domain Name Mapping Extension for Strict Bundling Registration
RFC 9095

Document Type RFC - Informational (July 2021; No errata)
Authors Jiankang Yao  , Linlin Zhou  , Hongtao Li  , Ning Kong  , Wil Tan  , Jiagui Xie 
Last updated 2021-08-01
Replaces draft-ietf-regext-bundling-registration
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Independent Submission                                            J. Yao
Request for Comments: 9095                                       L. Zhou
Category: Informational                                            H. Li
ISSN: 2070-1721                                                    CNNIC
                                                                 N. Kong
                                                              Consultant
                                                                  J. Xie
                                                               July 2021

Extensible Provisioning Protocol (EPP) Domain Name Mapping Extension for
                      Strict Bundling Registration

Abstract

   This document describes an extension of Extensible Provisioning
   Protocol (EPP) domain name mapping for the provisioning and
   management of strict bundling registration of domain names.
   Specified in XML, this mapping extends the EPP domain name mapping to
   provide additional features required for the provisioning of bundled
   domain names.  This is a nonstandard proprietary extension.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not candidates for any level of Internet Standard;
   see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9095.

Copyright Notice

   Copyright (c) 2021 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.

Table of Contents

   1.  Introduction
   2.  Terminology
   3.  Overview
   4.  Requirement for Bundling Registration of Names
   5.  Object Attributes
     5.1.  RDN
     5.2.  BDN
   6.  EPP Command Mapping
     6.1.  EPP Query Commands
       6.1.1.  EPP <check> Command
       6.1.2.  EPP <info> Command
       6.1.3.  EPP <transfer> Query Command
     6.2.  EPP Transform Commands
       6.2.1.  EPP <create> Command
       6.2.2.  EPP <delete> Command
       6.2.3.  EPP <renew> Command
       6.2.4.  EPP <transfer> Command
       6.2.5.  EPP <update> Command
   7.  Formal Syntax
   8.  Internationalization Considerations
   9.  IANA Considerations
     9.1.  XML Namespace and XML Schema
       9.1.1.  BDN Namespace
       9.1.2.  BDN XML Schema
     9.2.  EPP Extension
   10. Security Considerations
   11. References
     11.1.  Normative References
     11.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   In RFC 4290 [RFC4290], the "variant(s)" are character(s) and/or
   string(s) that are treated as equivalent to the base character.  In
   this document, variants are those strings that are treated as
   equivalent to each other according to the domain name registration
   policy.  Bundled domain names are those that share the same Top-Level
   Domain (TLD) but whose second-level labels are variants or those that
   have identical second-level labels for which certain parameters are
   shared in different TLDs.  For example, the Public Interest Registry
   has requested to implement bundling of second-level domains for .NGO
   and .ONG.  So we have two kinds of bundled domain names.  The first
   one is in the form of "V-label.TLD", in which the second-level label
   (V-label) is a variant sharing the same TLD.  The second one is in
   the form of "LABEL.V-tld", in which the second-level label (LABEL)
   remains the same but ends with a different TLD (V-tld) and these
   different V-tlds are managed by the same entity.

   Bundled domain names normally share some attributes.  Policy-wise
   bundling can be implemented in three ways.  The first one is strict
   bundling, which requires all bundled names to share many of the same
   attributes.  When creating, updating, or transferring any of the
   bundled domain names, all bundled domain names will be created,
   updated, or transferred atomically.  The second one is partial
   bundling, which requires the bundled domain names to be registered by
   the same registrant.  The third one is relaxed bundling, which has no
   specific requirements on the domain registration.  This document
   mainly addresses the strict bundling name registration.

   For the name variants, different registries have different policies.
   Some registries adopt the policy that variant Internationalized
   Domain Names (IDNs) should be blocked.  But some registries adopt the
   policy that variant IDNs that are identified as equivalent are
   allocated or delegated to the same registrant.  For example, most
   registries offering a Chinese Domain Name (CDN) adopt a registration
   policy whereby a registrant can apply for an original CDN in any
   form: Simplified Chinese (SC) form, Traditional Chinese (TC) form, or
   other variant forms.  The corresponding variant CDN in SC form and in
   TC form will also be delegated to the same registrant.  All variant
   names in the same TLD share a common set of attributes.  This
   document mainly discusses the situation in which variant IDNs that
   are identified as equivalent are allocated or delegated to the same
   registrant.

   The basic Extensible Provisioning Protocol (EPP) domain name mapping
   [RFC5731] provides the facility for single domain name registration.
   It does not specify how to register the strict bundled names that
   share many of the attributes.

   In order to meet the above requirements of strict bundled name
   registration, this document describes an extension of the EPP domain
   name mapping [RFC5731] for the provisioning and management of bundled
   names.  This document describes a nonstandard proprietary extension.
   This extension is especially useful for registries performing Chinese
   Domain Name registration.  This method is also useful for other
   language domain names that have similar issues with Chinese Domain
   Names.  This document is specified using 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].

   The EPP core protocol specification [RFC5730] provides a complete
   description of EPP command and response structures.  A thorough
   understanding of the base protocol specification is necessary to
   understand the extension mapping described in this document.

   This document uses many IDN concepts, so a thorough understanding of
   the IDNs for Application (IDNA, described in [RFC5890], [RFC5891],
   and [RFC5892]) and the variant approach discussed in [RFC4290] is
   assumed.

2.  Terminology

   Variants in this document are those strings that are treated as
   equivalent to each other according to the domain name registration
   policy for certain TLDs.

   Bundled domain names are bundled together according to the domain
   name registration policy.  For example, many Chinese Domain Name
   registries follow the principle described in RFC 3743 [RFC3743].
   Bundled domain names should belong to the same owner.  If bundled
   domain names are under different TLDs, those TLDs should be managed
   by the same entity.

   The terms "registered domain name" (RDN) and "bundled domain name"
   (BDN) are used in this document.  RDN represents the valid domain
   name that registrants submitted for the initial registration.  BDN
   represents the bundled domain name produced according to the bundled
   domain name registration policy.  In current practice, the number of
   BDNs is usually kept at one according to the registration policy set
   by the registry.  Both the RDN and BDN specified in this document
   will be registered via EPP.  All other domain names related to the
   RDN will be blocked.

   The "uLabel" attribute in this document is used to express the
   U-label of an Internationalized Domain Name as a series of characters
   where non-ASCII characters will be represented in the format of
   "&#xXXXX;" where XXXX is a Unicode point by using the XML escaping
   mechanism.  The U-label is defined in [RFC5890].  This document
   chooses this format of literal HTML ampersand codes, not the expected
   Unicode character codes.  Unicode characters may not be displayed
   correctly in some text file readers, while HTML numeric character
   references are easy for HTML processors.  The implementation
   following this document should use Unicode characters directly.

   This document uses the prefix "b-dn" for the namespace
   "urn:ietf:params:xml:ns:epp:b-dn" throughout.  Implementations cannot
   assume that any particular prefix is used and must employ a
   namespace-aware XML parser and serializer to interpret and output the
   XML documents.

   In the examples, "C:" represents lines sent by a protocol client, and
   "S:" represents lines returned by a protocol server.  Indentation and
   spacing in the examples are provided only to illustrate element
   relationships and are not a required feature of this specification.

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

3.  Overview

   Domain registries have usually adopted a registration model whereby
   metadata relating to a domain name, such as its expiration date and
   sponsoring registrar, are stored as properties of the domain object.
   The domain object is then considered an atomic unit of registration
   on which operations such as update, renewal, and deletion may be
   performed.

   Bundled names brought about the need for multiple domain names to be
   registered and managed as a single package.  In this model, the
   registry typically accepts a domain registration request (i.e., EPP
   domain <create> command) containing the domain name to be registered.
   This domain name is referred to as the RDN in this document.  As part
   of the processing of the registration request, the registry generates
   a set of bundled names that are related to the RDN, either
   programmatically or with the guidance of registration policies, and
   places them in the registration package together with the RDN.

   The bundled names share many properties, such as expiration date and
   sponsoring registrar, by sharing the same domain object.  So when
   registrants update any property of a domain object within a bundle
   package, that property will be updated at the same time for all other
   domain objects in the bundle package.

4.  Requirement for Bundling Registration of Names

   The bundled names, whether they are in the form of "V-label.TLD" or
   "LABEL.V-tld", should share some parameters or attributes associated
   with domain names.  Typically, bundled names will share the following
   parameters or attributes:

   *  Registrar ownership

   *  Registration and expiry dates

   *  Registrant, admin, billing, and technical contacts

   *  Name server association

   *  Domain status

   *  Applicable grace periods (add grace period, renew grace period,
      auto-renew grace period, transfer grace period, and redemption
      grace period) [RFC3915]

   Because the domain names are bundled and share the same parameters or
   attributes, the EPP command should do some processing for these
   requirements:

   *  When performing a domain <check> command, either the BDN or RDN
      can be queried with the EPP command and will return the same
      response.

   *  When performing a domain <info> command, either the BDN or RDN can
      be queried, and the same response will include both BDN and RDN
      information with the same attributes.

   *  When performing a domain <create> command, if the domain name is
      available, both the BDN and RDN will be registered.

   *  When performing a domain <delete> command, either the BDN or RDN
      will be accepted.  If the domain name is registered, both the BDN
      and RDN will be deleted.

   *  When performing a domain <renew> command, either the BDN or RDN
      will be accepted.  Upon a successful domain renewal, both the BDN
      and RDN will have their expiry date extended by the requested
      term.  Upon a successful domain renewal, both the BDN and RDN will
      conform to the same renew grace period.

   *  When performing a domain <transfer> command, either the BDN or RDN
      will be accepted.  Upon successful completion of a domain transfer
      request, both the BDN and RDN will enter a pendingTransfer status.
      Upon approval of the transfer request, both the BDN and RDN will
      be owned and managed by the same new registrant.

   *  When performing a domain <update> command, either the BDN or RDN
      will be accepted.  Any modifications to contact associations, name
      server associations, domain status values, and authorization
      information will be applied to both the BDN and RDN.

5.  Object Attributes

   This extension defines the following additional elements to the EPP
   domain name mapping [RFC5731].  All of these additional elements are
   returned from the <domain:info> command.

5.1.  RDN

   The RDN is an ASCII name or an IDN with the A-label [RFC5890] form.
   In this document, its corresponding element is <b-dn:rdn>.  An
   optional attribute "uLabel" associated with <b-dn:rdn> is used to
   represent the U-label [RFC5890] form.

   For example:

   <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example"> xn--
      fsq270a.example</b-dn:rdn>

5.2.  BDN

   The BDN is an ASCII name or an IDN with the A-label [RFC5890] form
   that is converted from the corresponding BDN.  In this document, its
   corresponding element is <b-dn:bdn>.  An optional attribute "uLabel"
   associated with <b-dn:bdn> is used to represent the U-label [RFC5890]
   form.

   For example:

   <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example"> xn--
      fsqz41a.example</b-dn:bdn>

6.  EPP Command Mapping

   A detailed description of the EPP syntax and semantics can be found
   in the EPP core protocol specification [RFC5730].  The command
   mappings described here are specifically for use in provisioning and
   managing bundled names via EPP.

6.1.  EPP Query Commands

   EPP provides three commands to retrieve domain information: <check>
   to determine if a domain object can be provisioned within a
   repository, <info> to retrieve detailed information associated with a
   domain object, and <transfer> to retrieve domain-object transfer
   status information.

6.1.1.  EPP <check> Command

   This extension does not add any element to the EPP <check> command or
   <check> response described in the EPP domain name mapping [RFC5731].
   However, when either the RDN or BDN is sent for a check, the response
   should contain both RDN and BDN information, which may also give some
   explanation in the reason field to tell the registrant that the
   associated domain name is a produced name according to some bundle
   domain name policy.

   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">
   S:            xn--fsq270a.example</domain:name>
   S:          </domain:cd>
   S:          <domain:cd>
   S:            <domain:name avail="1">
   S:              xn--fsqz41a.example
   S:            </domain:name>
   S:            <domain:reason>This associated domain name is
   S:              a produced name based on bundle name policy.
   S:            </domain:reason>
   S:          </domain:cd>
   S:      </domain:chkData>
   S:    </resData>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

                     Figure 1: Example <check> Response

6.1.2.  EPP <info> Command

   This extension does not add any element to the EPP <info> command
   described in the EPP domain mapping [RFC5731].  However, additional
   elements are defined for the <info> response.

   When an <info> command has been processed successfully, the EPP
   <resData> element must contain child elements as described in the EPP
   domain mapping [RFC5731].  In addition, unless some registration
   policy has some special processing, the EPP <extension> element
   should contain a child <b-dn:infData> element that identifies the
   extension namespace if the domain object has data associated with
   this extension and based on its registration policy.  The
   <b-dn:infData> element contains the <b-dn:bundle>, which has the
   following child elements:

   *  A <b-dn:rdn> element that contains the RDN, along with the
      attribute described below.

   *  An optional <b-dn:bdn> element that contains the BDN, along with
      the attribute described below.

   The above elements contain the following attribute:

   *  An optional "uLabel" attribute represents the U-label of the
      element.

   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:infData
   S:        xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
   S:        <domain:name>xn--fsq270a.example</domain:name>
   S:        <domain:roid>58812678-domain</domain:roid>
   S:        <domain:status s="ok"/>
   S:        <domain:registrant>123</domain:registrant>
   S:        <domain:contact type="admin">123</domain:contact>
   S:        <domain:contact type="tech">123</domain:contact>
   S:        <domain:ns>
   S:          <domain:hostObj>ns1.example.cn
   S:          </domain:hostObj>
   S:        </domain:ns>
   S:        <domain:clID>ClientX</domain:clID>
   S:        <domain:crID>ClientY</domain:crID>
   S:        <domain:crDate>2019-04-03T22:00:00.0Z
   S:        </domain:crDate>
   S:        <domain:exDate>2022-04-03T22:00:00.0Z
   S:        </domain:exDate>
   S:        <domain:authInfo>
   S:          <domain:pw>2fooBAR</domain:pw>
   S:        </domain:authInfo>
   S:      </domain:infData>
   S:    </resData>
   S:    <extension>
   S:      <b-dn:infData
   S:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   S:        <b-dn:bundle>
   S:          <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example">
   S:            xn--fsq270a.example
   S:          </b-dn:rdn>
   S:          <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example">
   S:            xn--fsqz41a.example
   S:          </b-dn:bdn>
   S:        </b-dn:bundle>
   S:      </b-dn:infData>
   S:    </extension>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

         Figure 2: Example <info> Response for an Authorized Client

   The <info> response for the unauthorized client has not been changed,
   see [RFC5731] for details.

   An EPP error response must be returned if an <info> command cannot be
   processed for any reason.

6.1.3.  EPP <transfer> Query Command

   This extension does not add any element to the EPP <transfer> command
   or <transfer> response described in the EPP domain mapping [RFC5731].

6.2.  EPP Transform Commands

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

   When these commands have been processed successfully, the EPP
   <resData> element must contain child elements as described in the EPP
   domain mapping [RFC5731].  Unless some registration policy has some
   special processing, this EPP <extension> element should contain the
   <b-dn:bundle>, which has the following child elements:

   *  A <b-dn:rdn> element that contains the RDN, along with the
      attribute described below.

   *  An optional <b-dn:bdn> element that contains the BDN, along with
      the attribute described below.

   The above elements contain the following attribute:

   *  An optional "uLabel" attribute represents the U-label of the
      element.

6.2.1.  EPP <create> Command

   This extension defines additional elements to extend the EPP <create>
   command described in the EPP domain name mapping [RFC5731] for
   bundled names registration.

   In addition to the EPP command elements described in the EPP domain
   mapping [RFC5731], the <create> command shall contain an <extension>
   element.  Unless some registration policy has some special
   processing, the <extension> element should contain a child
   <b-dn:create> element that identifies the bundle namespace and a
   child <b-dn:rdn> element that identifies the U-label form of the
   registered domain name with the "uLabel" attribute.  The U-label is
   used for easy reading by the registrants and easy debugging by the
   registrars and the registries.

   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>xn--fsq270a.example</domain:name>
   C:        <domain:period unit="y">2</domain:period>
   C:        <domain:registrant>123</domain:registrant>
   C:        <domain:contact type="admin">123</domain:contact>
   C:        <domain:contact type="tech">123</domain:contact>
   C:        <domain:authInfo>
   C:          <domain:pw>2fooBAR</domain:pw>
   C:        </domain:authInfo>
   C:      </domain:create>
   C:    </create>
   C:    <extension>
   C:      <b-dn:create
   C:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   C:        <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example">
   C:          xn--fsq270a.example
   C:        </b-dn:rdn>
   C:      </b-dn:create>
   C:    </extension>
   C:    <clTRID>ABC-12345</clTRID>
   C:  </command>
   C:</epp>

                     Figure 3: Example <create> Command

   When a <create> command has been processed successfully, the EPP
   <creData> element must contain child elements as described in the EPP
   domain mapping [RFC5731].  In addition, unless some registration
   policy has some special processing, the EPP <extension> element
   should contain a child <b-dn:creData> element that identifies the
   extension namespace if the domain object has data associated with
   this extension and based on its registration policy.  The
   <b-dn:creData> element contains the <b-dn:bundle> element.

   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>xn--fsq270a.example</domain:name>
   S:        <domain:crDate>2019-04-03T22:00:00.0Z</domain:crDate>
   S:        <domain:exDate>2021-04-03T22:00:00.0Z</domain:exDate>
   S:      </domain:creData>
   S:    </resData>
   S:    <extension>
   S:      <b-dn:creData
   S:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   S:        <b-dn:bundle>
   S:          <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example">
   S:            xn--fsq270a.example
   S:          </b-dn:rdn>
   S:          <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example" >
   S:            xn--fsqz41a.example
   S:          </b-dn:bdn>
   S:        </b-dn:bundle>
   S:      </b-dn:creData>
   S:    </extension>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

                    Figure 4: Example <create> Response

   An EPP error response must be returned if a <create> command cannot
   be processed for any reason.

6.2.2.  EPP <delete> Command

   This extension does not add any element to the EPP <delete> command
   described in the EPP domain mapping [RFC5731].  However, additional
   elements are defined for the <delete> response.

   When a <delete> command has been processed successfully, the EPP
   <delData> element must contain child elements as described in the EPP
   domain mapping [RFC5731].  In addition, unless some registration
   policy has some special processing, the EPP <extension> element
   should contain a child <b-dn:delData> element that identifies the
   extension namespace if the domain object has data associated with
   this extension and based on its registration policy.  The
   <b-dn:delData> element should contain the <b-dn:bundle> element.

   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:      <b-dn:delData
   S:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   S:        <b-dn:bundle>
   S:          <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example">
   S:            xn--fsq270a.example
   S:          </b-dn:rdn>
   S:          <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example">
   S:            xn--fsqz41a.example
   S:          </b-dn:bdn>
   S:        </b-dn:bundle>
   S:      </b-dn:delData>
   S:    </extension>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54321-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

                    Figure 5: Example <delete> Response

   An EPP error response must be returned if a <delete> command cannot
   be processed for any reason.

6.2.3.  EPP <renew> Command

   This extension does not add any element to the EPP <renew> command
   described in the EPP domain name mapping [RFC5731].  However, when
   either the RDN or BDN is sent for renewal, the response should
   contain both RDN and BDN information.  When the command has been
   processed successfully, the EPP <extension> element shall be
   contained in the response if the domain object has data associated
   with bundled names.  Unless some registration policy has some special
   processing, this EPP <extension> element should contain the
   <b-dn:renData>, which contains the <b-dn:bundle> element.

   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>xn--fsq270a.example</domain:name>
   S:        <domain:exDate>2022-04-03T22:00:00.0Z</domain:exDate>
   S:      </domain:renData>
   S:    </resData>
   S:    <extension>
   S:      <b-dn:renData
   S:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   S:        <b-dn:bundle>
   S:          <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example">
   S:            xn--fsq270a.example
   S:          </b-dn:rdn>
   S:          <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example" >
   S:            xn--fsqz41a.example
   S:          </b-dn:bdn>
   S:        </b-dn:bundle>
   S:      </b-dn:renData>
   S:    </extension>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

                     Figure 6: Example <renew> Response

6.2.4.  EPP <transfer> Command

   This extension does not add any element to the EPP <transfer> command
   described in the EPP domain name mapping [RFC5731].  However,
   additional elements are defined for the <transfer> response in the
   EPP object mapping.  When the command has been processed
   successfully, the EPP <extension> element shall be contained in the
   response if the domain object has data associated with bundled names.
   Unless some registration policy has some special processing, this EPP
   <extension> element should contain the <b-dn:trnData>, which contains
   the <b-dn:bundle> element.

   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>xn--fsq270a.example</domain:name>
   S:        <domain:trStatus>pending</domain:trStatus>
   S:        <domain:reID>ClientX</domain:reID>
   S:        <domain:reDate>2021-04-03T22:00:00.0Z</domain:reDate>
   S:        <domain:acID>ClientY</domain:acID>
   S:        <domain:acDate>2021-04-08T22:00:00.0Z</domain:acDate>
   S:        <domain:exDate>2022-04-03T22:00:00.0Z</domain:exDate>
   S:      </domain:trnData>
   S:    </resData>
   S:    <extension>
   S:      <b-dn:trnData
   S:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   S:        <b-dn:bundle>
   S:          <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example">
   S:            xn--fsq270a.example
   S:          </b-dn:rdn>
   S:          <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example">
   S:            xn--fsqz41a.example
   S:          </b-dn:bdn>
   S:        </b-dn:bundle>
   S:      </b-dn:trnData>
   S:    </extension>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

                   Figure 7: Example <transfer> Response

6.2.5.  EPP <update> Command

   This extension does not add any element to the EPP <update> command
   described in the EPP domain name mapping [RFC5731].  However,
   additional elements are defined for the <update> response in the EPP
   object mapping.  When the command has been processed successfully,
   the EPP <extension> element shall be contained in the response if the
   domain object has data associated with bundled names.  Unless some
   registration policy has some special processing, this EPP <extension>
   element should contain the <b-dn:upData>, which contains the
   <b-dn:bundle> element.

   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:      <b-dn:upData
   S:        xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn">
   S:        <b-dn:bundle>
   S:          <b-dn:rdn uLabel="&#x5B9E;&#x4F8B;.example" >
   S:            xn--fsq270a.example
   S:          </b-dn:rdn>
   S:          <b-dn:bdn uLabel="&#x5BE6;&#x4F8B;.example">
   S:            xn--fsqz41a.example
   S:          </b-dn:bdn>
   S:        </b-dn:bundle>
   S:      </b-dn:upData>
   S:    </extension>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

                    Figure 8: Example <update> Response

7.  Formal Syntax

   An EPP object name mapping extension for bundled names is specified
   in XML Schema notation.  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.

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

   <schema targetNamespace="urn:ietf:params:xml:ns:epp:b-dn"
     xmlns:b-dn="urn:ietf:params:xml:ns:epp:b-dn"
     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:iana:xml:ns:eppcom-1.0"/>

   <annotation>
     <documentation>
       Extensible Provisioning Protocol v1.0
       Bundle Domain Extension Schema v1.0
     </documentation>
   </annotation>

   <!--
     Child elements found in EPP commands.
   -->
   <element name="create" type="b-dn:createDataType"/>

   <!--
     Child elements of the <b-dn:create> command.
     All elements must be present at time of creation
   -->
   <complexType name="createDataType">
     <sequence>
       <element name="rdn" type="b-dn:rdnType"
         minOccurs="0"/>
     </sequence>
   </complexType>

   <!--
     Child response elements in <b-dn:infData>, <b-dn:delData>,
     <b-dn:creData>, <b-dn:renData>, <b-dn:trnData> and <b-dn:upData>.
   -->
   <element name="infData" type="b-dn:bundleDataType"/>
   <element name="delData" type="b-dn:bundleDataType"/>
   <element name="creData" type="b-dn:bundleDataType"/>
   <element name="renData" type="b-dn:bundleDataType"/>
   <element name="trnData" type="b-dn:bundleDataType"/>
   <element name="upData" type="b-dn:bundleDataType"/>

   <complexType name="bundleDataType">
     <sequence>
       <element name="bundle" type="b-dn:bundleType" />
     </sequence>
   </complexType>

   <complexType name="bundleType">
     <sequence>
       <element name="rdn" type="b-dn:rdnType" />
       <element name="bdn" type="b-dn:rdnType"
         minOccurs="0" maxOccurs="unbounded" />
     </sequence>
   </complexType>

   <complexType name="rdnType">
     <simpleContent>
       <extension base="eppcom:labelType">
         <attribute name="uLabel" type="eppcom:labelType"/>
       </extension>
     </simpleContent>
   </complexType>

   <!--
     End of schema.
   -->
   </schema>
   <CODE ENDS>

8.  Internationalization Considerations

   EPP is represented in XML, which provides 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.

   As an extension of the EPP domain name mapping, the elements and
   element content described in this document must inherit the
   internationalization conventions used to represent higher-layer
   domain and core protocol structures present in an XML instance that
   includes this extension.

9.  IANA Considerations

9.1.  XML Namespace and XML Schema

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

9.1.1.  BDN Namespace

   IANA has assigned the following for the BDN namespace in the "ns"
   subregistry of the "IETF XML Registry", with this document as the
   reference:

   URI:  urn:ietf:params:xml:ns:epp:b-dn
   Registrant Contact:  See the "Authors' Addresses" section of this
      document.
   XML:  None.  The namespace URI does not represent an XML
      specification.

9.1.2.  BDN XML Schema

   IANA has made the following assignment in the "schema" subregistry of
   the "IETF XML Registry" for the BDN XML schema, with this document as
   the reference:

   URI:  urn:ietf:params:xml:schema:epp:b-dn
   Registrant Contact:  See the "Authors' Addresses" section of this
      document.
   XML:  See the "Formal Syntax" section of this document.

9.2.  EPP Extension

   IANA has registered the EPP extension described in this document in
   the "Extensions for the Extensible Provisioning Protocol (EPP)"
   registry described in [RFC7451].  The details of the registration are
   as follows:

   Name of Extension:  "Domain Name Mapping Extension for Strict
      Bundling Registration"
   Document Status:  Informational
   Reference:  This document
   Registrant Name and Email Address:  See the "Authors' Addresses"
      section of this document.
   TLDs:  Any
   IPR Disclosure:  https://datatracker.ietf.org/ipr/2479
   Status:  Active
   Notes:  None

10.  Security Considerations

   Normally, the EPP server will only be connected by the authorized EPP
   client, which knows whether the EPP server supports the extension
   described in this document via out-of-band service.  The EPP client
   should avoid sending this extension to the unimplemented EPP server.
   In case a client that supports this document sends a request to a
   server that does not support this document, the server will return
   the result code 2103 according to Section 3 of [RFC5730].  Section 3
   of [RFC5730] has the following information for result code 2103.

   |  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.

   Some registries and registrars have more than 15 years' experience
   with the bundled registration of domain names (especially Chinese
   Domain Names).  They have not found any significant security issues.
   One principle that the registry and registrar should let the
   registrants know is that bundled registered domain names will be
   created, transferred, updated, and deleted together as a group.  The
   registrants for bundled domain names should remember this principle
   when performing operations to these domain names.  [RFC5730] also
   introduces some security consideration.

   This document does not take a position regarding whether or not the
   bundled domain names share a key for Delegation Signer (DS) and/or
   DNS Public Key (DNSKEY) resource records.  The DNS administrator can
   choose whether DS/DNSKEY information can be shared or not.  If a DS/
   DNSKEY key is shared, then the bundled domain names share fate if
   there is a key compromise.

11.  References

11.1.  Normative References

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

   [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>.

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, DOI 10.17487/RFC5890, August 2010,
              <https://www.rfc-editor.org/info/rfc5890>.

   [RFC5891]  Klensin, J., "Internationalized Domain Names in
              Applications (IDNA): Protocol", RFC 5891,
              DOI 10.17487/RFC5891, August 2010,
              <https://www.rfc-editor.org/info/rfc5891>.

   [RFC5892]  Faltstrom, P., Ed., "The Unicode Code Points and
              Internationalized Domain Names for Applications (IDNA)",
              RFC 5892, DOI 10.17487/RFC5892, August 2010,
              <https://www.rfc-editor.org/info/rfc5892>.

   [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>.

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

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

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

11.2.  Informative References

   [RFC3743]  Konishi, K., Huang, K., Qian, H., and Y. Ko, "Joint
              Engineering Team (JET) Guidelines for Internationalized
              Domain Names (IDN) Registration and Administration for
              Chinese, Japanese, and Korean", RFC 3743,
              DOI 10.17487/RFC3743, April 2004,
              <https://www.rfc-editor.org/info/rfc3743>.

   [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>.

   [RFC4290]  Klensin, J., "Suggested Practices for Registration of
              Internationalized Domain Names (IDN)", RFC 4290,
              DOI 10.17487/RFC4290, December 2005,
              <https://www.rfc-editor.org/info/rfc4290>.

Acknowledgements

   The authors especially thank the authors of [RFC5730] and [RFC5731]
   and the following members of the China Internet Network Information
   Center (CNNIC): Weiping Yang, Chao Qi.

   Useful comments were made by John Klensin, Scott Hollenbeck, Patrick
   Mevzek, Edward Lewis, Wil Tan, and Adrian Farrel.

Authors' Addresses

   Jiankang Yao
   CNNIC
   4 South 4th Street, Zhongguancun, Haidian District
   Beijing
   Beijing, 100190
   China

   Phone: +86 10 5881 3007
   Email: yaojk@cnnic.cn

   Linlin Zhou
   CNNIC
   4 South 4th Street, Zhongguancun, Haidian District
   Beijing
   Beijing, 100190
   China

   Phone: +86 10 5881 2677
   Email: zhoulinlin@cnnic.cn

   Hongtao Li
   CNNIC
   4 South 4th Street, Zhongguancun, Haidian District
   Beijing
   Beijing, 100190
   China

   Email: lihongtao@cnnic.cn

   Ning Kong
   Consultant

   Email: ietfing@gmail.com

   Jiagui Xie

   Email: jiagui1984@163.com