Network Working Group                                     S. Hollenbeck
Request for Comments: 4930                               VeriSign, Inc.
Obsoletes: 3730                                                May 2007
Category: Standards Track

                 Extensible Provisioning Protocol (EPP)

Status of This Memo

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

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document describes an application layer client-server protocol
   for the provisioning and management of objects stored in a shared
   central repository.  Specified in XML, the protocol defines generic
   object management operations and an extensible framework that maps
   protocol operations to objects.  This document includes a protocol
   specification, an object mapping template, and an XML media type
   registration.  This document obsoletes RFC 3730.

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RFC 4930                          EPP                          May 2007

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Conventions Used in This Document  . . . . . . . . . . . . 3
   2.  Protocol Description . . . . . . . . . . . . . . . . . . . . . 4
     2.1.  Transport Mapping Considerations . . . . . . . . . . . . . 7
     2.2.  Protocol Identification  . . . . . . . . . . . . . . . . . 8
     2.3.  Hello Format . . . . . . . . . . . . . . . . . . . . . . . 8
     2.4.  Greeting Format  . . . . . . . . . . . . . . . . . . . . . 8
     2.5. Command Format . . . . . . . . . . . . . . . . . . . . . . 12
     2.6.  Response Format . . . . . . . . . . . . . . . . . . . . . 13
     2.7. Protocol Extension Framework . . . . . . . . . . . . . . . 18
       2.7.1. Protocol Extension . . . . . . . . . . . . . . . . . . 18
       2.7.2. Object Extension . . . . . . . . . . . . . . . . . . . 18
       2.7.3. Command-Response Extension . . . . . . . . . . . . . . 19
     2.8.  Object Identification . . . . . . . . . . . . . . . . . . 20
     2.9.  Protocol Commands . . . . . . . . . . . . . . . . . . . . 21
       2.9.1.  Session Management Commands . . . . . . . . . . . . . 21
         2.9.1.1.  EPP <login> Command . . . . . . . . . . . . . . . 21
         2.9.1.2. EPP <logout> Command . . . . . . . . . . . . . . . 24
       2.9.2. Query Commands . . . . . . . . . . . . . . . . . . . . 25
         2.9.2.1.  EPP <check> Command . . . . . . . . . . . . . . . 25
         2.9.2.2. EPP <info> Command . . . . . . . . . . . . . . . . 27
         2.9.2.3. EPP <poll> Command . . . . . . . . . . . . . . . . 28
         2.9.2.4. EPP <transfer> Query Command . . . . . . . . . . . 32
       2.9.3.  Object Transform Commands . . . . . . . . . . . . . . 34
         2.9.3.1. EPP <create> Command . . . . . . . . . . . . . . . 34
         2.9.3.2. EPP <delete> Command . . . . . . . . . . . . . . . 36
         2.9.3.3.  EPP <renew> Command . . . . . . . . . . . . . . . 37
         2.9.3.4. EPP <transfer> Command . . . . . . . . . . . . . . 39
         2.9.3.5. EPP <update> Command . . . . . . . . . . . . . . . 41
   3. Result Codes . . . . . . . . . . . . . . . . . . . . . . . . . 42
   4.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 48
     4.1.  Base Schema . . . . . . . . . . . . . . . . . . . . . . . 48
     4.2.  Shared Structure Schema . . . . . . . . . . . . . . . . . 58
   5.  Internationalization Considerations . . . . . . . . . . . . . 60
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . 61
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . 62
   8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 63
   9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 63
     9.1. Normative References . . . . . . . . . . . . . . . . . . . 63
     9.2. Informative References . . . . . . . . . . . . . . . . . . 64
   Appendix A. Object Mapping Template . . . . . . . . . . . . . . . 66
   Appendix B.  Media Type Registration: application/epp+xml . . . . 68
   Appendix C. Changes from RFC 3730 . . . . . . . . . . . . . . . . 69

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1.  Introduction

   This document describes specifications for the Extensible
   Provisioning Protocol (EPP) version 1.0, an XML text protocol that
   permits multiple service providers to perform object provisioning
   operations using a shared central object repository.  EPP is
  specified using the Extensible Markup Language (XML) 1.0 as described
   in [W3C.REC-xml-20040204] and XML Schema notation as described in
   [W3C.REC-xmlschema-1-20041028] and [W3C.REC-xmlschema-2-20041028].
   EPP meets and exceeds the requirements for a generic registry
   registrar protocol as described in [RFC3375].  This document
   obsoletes RFC 3730 [RFC3730].

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

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

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

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

1.1.  Conventions Used in This Document

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

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

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2.  Protocol Description

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

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

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

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

   Figure 1: EPP Server State Machine

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

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

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

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

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

   Example XML declarations:

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

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

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

   <?xml version="1.0"?>

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2.1.  Transport Mapping Considerations

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

   -  The transport mapping MUST preserve command order.

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

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

   -  The transport mapping MUST frame data units.

   -  The transport mapping MUST be onto a transport such as TCP
     [RFC0793] or Stream Control Transmission Protocol (SCTP) [RFC2960]
      that provides congestion avoidance that follows RFC 2914
     [RFC2914], or if it maps onto a protocol such as SMTP [RFC2821] or
      Blocks Extensible Exchange Protocol (BEEP) [RFC3080], then the
      performance issues need to take into account issues of overload,
      server availability, and so forth.

   -  The transport mapping MUST ensure reliability.

   -  The transport mapping MUST explicitly allow or prohibit
      pipelining.

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

   -  Commands MUST be processed independent of each other.

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

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

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

2.2.  Protocol Identification

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

   Example "start" and "end" EPP elements:

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

2.3.  Hello Format

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

   Example <hello>:

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

2.4.  Greeting Format

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

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

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   -  An <svDate> element that contains the server's current date and
      time in UTC.

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

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

      - One or more <lang> elements that contain the identifiers of the
         text response languages known by the server.  Language
         identifiers MUST be structured as documented in [RFC3066].

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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            -  <public/>: Public forums.

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

            -  <unrelated/>: Unrelated third parties.

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

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

            -  <indefinite/>: Data persists indefinitely.

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

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

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

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

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

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

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

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   Example greeting:

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

2.5.  Command Format

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

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

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

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

   Example command with object-specified child elements:

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

2.6.  Response Format

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   Example response without <value> or <resData>:

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

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   Example response with <resData>:

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

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   Example response with error value elements:

   S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
   S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
   S:  <response>
   S:    <result code="2004">
   S:      <msg>Parameter value range error</msg>
   S:      <value xmlns:obj="urn:ietf:params:xml:ns:obj">
   S:        <obj:elem1>2525</obj:elem1>
   S:      </value>
   S:    </result>
   S:    <result code="2005">
   S:      <msg>Parameter value syntax error</msg>
   S:      <value xmlns:obj="urn:ietf:params:xml:ns:obj">
   S:        <obj:elem2>ex(ample</obj:elem2>
   S:      </value>
   S:      <extValue>
   S:        <value xmlns:obj="urn:ietf:params:xml:ns:obj">
   S:          <obj:elem3>abc.ex(ample</obj:elem3>
   S:        </value>
   S:        <reason>Invalid character found.</reason>
   S:      </extValue>
   S:    </result>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54321-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

   Example response with notice of waiting server messages:

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

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

2.7.  Protocol Extension Framework

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

2.7.1.  Protocol Extension

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

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

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

2.7.2.  Object Extension

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

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

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

   An object-specific response element would be described similarly:

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

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

2.7.3.  Command-Response Extension

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

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

   An server-extended response element would be described similarly:

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

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

2.8.  Object Identification

   Some objects, such as name servers and contacts, can have utility in
   multiple repositories.  However, maintaining disjoint copies of
   object information in multiple repositories can lead to
   inconsistencies that have adverse consequences for the Internet. For
   example, changing a name server name in one repository, but not in a
   second repository that refers to the server for domain name
   delegation, can produce unexpected DNS query results.

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

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

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

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

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

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2.9.  Protocol Commands

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

2.9.1.  Session Management Commands

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

2.9.1.1.  EPP <login> Command

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

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

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

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

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

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

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

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

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

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

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

   The PLAIN Simple Authentication and Security Layer (SASL) mechanism
   presented in [RFC2595] describes a format for providing a user
   identifier, an authorization identifier, and a password as part of a
   single plain text string.  The EPP authentication mechanism is
   similar, though EPP does not require a session-level authorization
   identifier and the user identifier and password are separated into
   distinct XML elements.  Additional identification and authorization
   schemes MUST be provided at other protocol layers to provide more
   robust security services.

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   Example <login> command:

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

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

   Example <login> response:

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

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

2.9.1.2.  EPP <logout> Command

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

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

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

   Example <logout> command:

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

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

   Example <logout> response:

   S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
   S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
   S:  <response>
   S:    <result code="1500">
   S:      <msg>Command completed successfully; ending session</msg>
   S:    </result>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54321-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

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

2.9.2.  Query Commands

2.9.2.1.  EPP <check> Command

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

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

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

   Example <check> command:

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

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

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

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

   Example <check> response:

   S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
   S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
   S:  <response>
   S:    <result code="1000">
   S:      <msg>Command completed successfully</msg>
   S:    </result>
   S:    <resData>
   S:      <obj:chkData xmlns:obj="urn:ietf:params:xml:ns:obj">
   S:        <obj:cd>
   S:          <obj:name avail="1">example1</obj:name>
   S:        </obj:cd>
   S:        <obj:cd>
   S:          <obj:name avail="0">example2</obj:name>
   S:          <obj:reason>In use</obj:reason>
   S:        </obj:cd>
   S:        <obj:cd>
   S:          <obj:name avail="1">example3</obj:name>
   S:        </obj:cd>
   S:      </obj:chkData>
   S:    </resData>
   S:    <trID>
   S:      <clTRID>ABC-12346</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

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

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2.9.2.2.  EPP <info> Command

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

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

   Example <info> command:

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

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

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   Example <info> response:

   S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
   S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
   S:  <response>
   S:    <result code="1000">
   S:      <msg>Command completed successfully</msg>
   S:    </result>
   S:    <resData>
   S:      <obj:infData xmlns:obj="urn:ietf:params:xml:ns:obj">
   S:        <obj:roid>EXAMPLE1-REP</obj:roid>
   S:        <!-- Object-specific elements. -->
   S:      </obj:infData>
   S:    </resData>
   S:    <trID>
   S:      <clTRID>ABC-12346</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

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

2.9.2.3.  EPP <poll> Command

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

   Servers can occasionally perform actions on objects that are not in
  direct response to a client request, or an action taken by one client
   can indirectly involve a second client.  Examples of such actions
   include deletion upon expiration, automatic renewal upon expiration,
   and transfer coordination; other types of service information MAY be
   defined as a matter of server policy.  Service messages SHOULD be

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   created for passive clients affected by an action on an object.
   Service messages MAY also be created for active clients that request
   an action on an object, though such messages MUST NOT replace the
   normal protocol response to the request.  For example, <transfer>
   actions SHOULD be reported to the client that has the authority to
   approve or reject a transfer request. Other methods of server-client
  action notification, such as offline reporting, are also possible and
   are beyond the scope of this specification.

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

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

   Example <poll> command:

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

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

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   Example <poll> response with object-specific information:

   S:<?xml version="1.0" encoding="UTF-8" standalone="no"?>
   S:<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
   S:  <response>
   S:    <result code="1301">
   S:      <msg>Command completed successfully; ack to dequeue</msg>
   S:    </result>
   S:    <msgQ count="5" id="12345">
   S:      <qDate>2000-06-08T22:00:00.0Z</qDate>
   S:      <msg>Transfer requested.</msg>
   S:    </msgQ>
   S:    <resData>
   S:      <obj:trnData
   S:       xmlns:obj="urn:ietf:params:xml:ns:obj-1.0">
   S:        <obj:name>example.com</obj:name>
   S:        <obj:trStatus>pending</obj:trStatus>
   S:        <obj:reID>ClientX</obj:reID>
   S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
   S:        <obj:acID>ClientY</obj:acID>
   S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
   S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
   S:      </obj:trnData>
   S:    </resData>
   S:    <trID>
   S:      <clTRID>ABC-12345</clTRID>
   S:      <svTRID>54321-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

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

   Example <poll> acknowledgement command:

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

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

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   Example <poll> acknowledgement response:

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

   Service messages can also be returned without object information.

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

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

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

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

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

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

2.9.2.4.  EPP <transfer> Query Command

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

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

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

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   Example <transfer> query command:

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

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

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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="1000">
   S:      <msg>Command completed successfully</msg>
   S:    </result>
   S:    <resData>
   S:      <obj:trnData xmlns:obj="urn:ietf:params:xml:ns:obj">
   S:        <obj:name>example</obj:name>
   S:        <obj:trStatus>pending</obj:trStatus>
   S:        <obj:reID>ClientX</obj:reID>
   S:        <obj:reDate>2000-06-08T22:00:00.0Z</obj:reDate>
   S:        <obj:acID>ClientY</obj:acID>
   S:        <obj:acDate>2000-06-13T22:00:00.0Z</obj:acDate>
   S:        <obj:exDate>2002-09-08T22:00:00.0Z</obj:exDate>
   S:      </obj:trnData>
   S:    </resData>
   S:    <trID>
   S:      <clTRID>ABC-12346</clTRID>
   S:      <svTRID>54322-XYZ</svTRID>
   S:    </trID>
   S:  </response>
   S:</epp>

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

2.9.3.  Object Transform Commands

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

2.9.3.1.  EPP <create> Command

   The EPP <create> command is used to create an instance of an object.
   An object can be created for an indefinite period of time, or an
   object can be created for a specific validity period.  The EPP
   mapping for an object MUST describe the status of an object with

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   respect to time, to include expected client and server behavior if a
   validity period is used.

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

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

   Example <create> command:

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

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

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   Example <create> response with <resData>:

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

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

2.9.3.2.  EPP <delete> Command

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

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

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   Example <delete> command:

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

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

   Example <delete> response without <resData>:

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

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

2.9.3.3.  EPP <renew> Command

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

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

   Example <renew> command:

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

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

   Example <renew> response with <resData>:

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

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

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2.9.3.4.  EPP <transfer> Command

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

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

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

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

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

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

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

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

   Example <transfer> command:

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

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

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   Example <transfer> response with <resData>:

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

   The EPP <transfer> command is used to manage changes in client
   sponsorship of an existing object.  This action SHOULD be limited to
  authorized clients; restricting <transfer> requests to a client other
   than the current sponsoring client, <transfer> approval requests to
   the current sponsoring client, and <transfer> cancellation requests
   to the original requesting client is RECOMMENDED.  Object transfer
   MAY be unavailable or limited by object-specific policies.

2.9.3.5.  EPP <update> Command

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

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

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   Example <update> command:

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

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

   Example <update> response without <resData>:

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

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

3.  Result Codes

   EPP result codes are based on the theory of reply codes described in
   section 4.2.1 of [RFC2821]. EPP uses four decimal digits to describe
   the success or failure of each EPP command.  Each of the digits of
   the reply have special significance.

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

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

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

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

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

   x0zz    Protocol Syntax
   x1zz    Implementation-specific Rules
   x2zz    Security
   x3zz    Data Management
   x4zz    Server System
   x5zz    Connection Management

   The third and fourth digits provide response detail within the
   categories defined by the first and second digits.  Specific result
   codes are listed in the table below.

   Every EPP response MUST include a result code and a human-readable
   description of the result code.  The language used to represent the
   description MAY be identified using an instance of the "lang"
   attribute within the <msg> element.  If not specified, the default
   language is English, identified as "en".  A description of the
   structure of valid values for the "lang" attribute is described in
   [RFC3066].

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

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

   Successful command completion responses:

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   Code    Response text in English
   ____    ________________________

   1000    "Command completed successfully"
           This is the usual response code for a successfully completed
           command that is not addressed by any other 1xxx-series
           response code.

   1001    "Command completed successfully; action pending"
           This response code MUST be returned when responding to a
           command that requires offline activity before the requested
           action can be completed.  See Section 2 for a description of
           other processing requirements.

   1300    "Command completed successfully; no messages"
           This response code MUST be returned when responding to a
          <poll> request command and the server message queue is empty.

   1301    "Command completed successfully; ack to dequeue"
           This response code MUST be returned when responding to a
           <poll> request command and a message has been retrieved from
           the server message queue.

   1500    "Command completed successfully; ending session"
           This response code MUST be returned when responding to a
           successful <logout> command.

   Command error responses:

   Code    Response text in English
   ____    ________________________

   2000    "Unknown command"
           This response code MUST be returned when a server receives a
           command element that is not defined by EPP.

   2001    "Command syntax error"
          This response code MUST be returned when a server receives an
           improperly formed command element.

   2002    "Command use error"
           This response code MUST be returned when a server receives a
           properly formed command element, but the command cannot be
           executed due to a sequencing or context error.  For example,
           a <logout> command cannot be executed without having first
           completed a <login> command.

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   2003    "Required parameter missing"
           This response code MUST be returned when a server receives a
           command for which a required parameter value has not been
           provided.

   2004    "Parameter value range error"
           This response code MUST be returned when a server receives a
           command parameter whose value is outside the range of values
           specified by the protocol.  The error value SHOULD be
           returned via a <value> element in the EPP response.

   2005    "Parameter value syntax error"
           This response code MUST be returned when a server receives a
           command containing a parameter whose value is improperly
           formed.  The error value SHOULD be returned via a <value>
           element in the EPP response.

   2100    "Unimplemented protocol version"
           This response code MUST be returned when a server receives a
           command element specifying a protocol version that is not
           implemented by the server.

   2101    "Unimplemented command"
           This response code MUST be returned when a server receives a
           valid EPP command element that is not implemented by the
           server.  For example, a <transfer> command can be
           unimplemented for certain object types.

   2102    "Unimplemented option"
           This response code MUST be returned when a server receives a
           valid EPP command element that contains a protocol option
           that is not implemented by the server.

   2103    "Unimplemented extension"
           This response code MUST be returned when a server receives a
           valid EPP command element that contains a protocol command
           extension that is not implemented by the server.

   2104    "Billing failure"
          This response code MUST be returned when a server attempts to
           execute a billable operation and the command cannot be
           completed due to a client billing failure.

   2105    "Object is not eligible for renewal"
          This response code MUST be returned when a client attempts to
           <renew> an object that is not eligible for renewal in
           accordance with server policy.

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   2106    "Object is not eligible for transfer"
          This response code MUST be returned when a client attempts to
           <transfer> an object that is not eligible for transfer in
           accordance with server policy.

   2200    "Authentication error"
           This response code MUST be returned when a server notes an
           error when validating client credentials.

   2201    "Authorization error"
           This response code MUST be returned when a server notes a
           client authorization error when executing a command.  This
           error is used to note that a client lacks privileges to
           execute the requested command.

   2202    "Invalid authorization information"
           This response code MUST be returned when a server receives
          invalid command authorization information required to confirm
           authorization to execute a command.  This error is used to
          note that a client has the privileges required to execute the
          requested command, but the authorization information provided
           by the client does not match the authorization information
           archived by the server.

   2300    "Object pending transfer"
           This response code MUST be returned when a server receives a
          command to transfer of an object that is pending transfer due
           to an earlier transfer request.

   2301    "Object not pending transfer"
           This response code MUST be returned when a server receives a
           command to confirm, reject, or cancel the transfer an object
           when no command has been made to transfer the object.

   2302    "Object exists"
           This response code MUST be returned when a server receives a
           command to create an object that already exists in the
           repository.

   2303    "Object does not exist"
           This response code MUST be returned when a server receives a
           command to query or transform an object that does not exist
           in the repository.

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   2304    "Object status prohibits operation"
           This response code MUST be returned when a server receives a
           command to transform an object that cannot be completed due
           to server policy or business practices.  For example, a
           server can disallow <transfer> commands under terms and
           conditions that are matters of local policy, or the server
           might have received a <delete> command for an object whose
           status prohibits deletion.

   2305    "Object association prohibits operation"
           This response code MUST be returned when a server receives a
           command to transform an object that cannot be completed due
          to dependencies on other objects that are associated with the
           target object.  For example, a server can disallow <delete>
           commands while an object has active associations with other
           objects.

   2306    "Parameter value policy error"
           This response code MUST be returned when a server receives a
           command containing a parameter value that is syntactically
           valid, but semantically invalid due to local policy.  For
           example, the server can support a subset of a range of valid
           protocol parameter values.  The error value SHOULD be
           returned via a <value> element in the EPP response.

   2307    "Unimplemented object service"
           This response code MUST be returned when a server receives a
          command to operate on an object service that is not supported
           by the server.

   2308    "Data management policy violation"
           This response code MUST be returned when a server receives a
          command whose execution results in a violation of server data
           management policies.  For example, removing all attribute
           values or object associations from an object might be a
           violation of a server's data management policies.

   2400    "Command failed"
           This response code MUST be returned when a server is unable
           to execute a command due to an internal server error that is
           not related to the protocol.  The failure can be transient.
           The server MUST keep any ongoing session active.

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   2500    "Command failed; server closing connection"
           This response code MUST be returned when a server receives a
           command that cannot be completed due to an internal server
           error that is not related to the protocol.  The failure is
           not transient and will cause other commands to fail as well.
          The server MUST end the active session and close the existing
           connection.

   2501    "Authentication error; server closing connection"
           This response code MUST be returned when a server notes an
          error when validating client credentials and a server-defined
           limit on the number of allowable failures has been exceeded.
           The server MUST close the existing connection.

   2502    "Session limit exceeded; server closing connection"
           This response code MUST be returned when a server receives a
           <login> command, and the command cannot be completed because
           the client has exceeded a system-defined limit on the number
           of sessions that the client can establish.  It might be
           possible to establish a session by ending existing unused
           sessions and closing inactive connections.

4.  Formal Syntax

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

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

4.1.  Base Schema

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

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

   <!--
   Import common element types.
   -->

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

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

   <!--
   Every EPP XML instance must begin with this element.
   -->
     <element name="epp" type="epp:eppType"/>

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

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

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

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     </simpleType>

   <!--
   A server greeting identifies available object services.
   -->
     <complexType name="svcMenuType">
       <sequence>
         <element name="version" type="epp:versionType"
          maxOccurs="unbounded"/>
         <element name="lang" type="language"
          maxOccurs="unbounded"/>
         <element name="objURI" type="anyURI"
          maxOccurs="unbounded"/>
         <element name="svcExtension" type="epp:extURIType"
          minOccurs="0"/>
       </sequence>
     </complexType>

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

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

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

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     </complexType>

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

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

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

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

     <complexType name="dcpRetentionType">
       <choice>
         <element name="business"/>
         <element name="indefinite"/>

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

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

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

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

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

   <!--
   Command types.
   -->
     <complexType name="commandType">
       <sequence>
         <choice>
           <element name="check" type="epp:readWriteType"/>
           <element name="create" type="epp:readWriteType"/>

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           <element name="delete" type="epp:readWriteType"/>
           <element name="info" type="epp:readWriteType"/>
           <element name="login" type="epp:loginType"/>
           <element name="logout"/>
           <element name="poll" type="epp:pollType"/>
           <element name="renew" type="epp:readWriteType"/>
           <element name="transfer" type="epp:transferType"/>
           <element name="update" type="epp:readWriteType"/>
         </choice>
         <element name="extension" type="epp:extAnyType"
          minOccurs="0"/>
         <element name="clTRID" type="epp:trIDStringType"
          minOccurs="0"/>
       </sequence>
     </complexType>

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

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

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

     <complexType name="loginSvcType">
       <sequence>
         <element name="objURI" type="anyURI"
          maxOccurs="unbounded"/>

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

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

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

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

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

   <!--
   All other object-centric commands. EPP doesn't specify the syntax or
   semantics of object-centric command elements.  The elements MUST be
   described in detail in another schema specific to the object.
   -->

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

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

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

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

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

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     </complexType>

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

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

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

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

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

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     </complexType>

   <!--
   EPP result codes.
   -->
     <simpleType name="resultCodeType">
       <restriction base="unsignedShort">
         <enumeration value="1000"/>
         <enumeration value="1001"/>
         <enumeration value="1300"/>
         <enumeration value="1301"/>
         <enumeration value="1500"/>
         <enumeration value="2000"/>
         <enumeration value="2001"/>
         <enumeration value="2002"/>
         <enumeration value="2003"/>
         <enumeration value="2004"/>
         <enumeration value="2005"/>
         <enumeration value="2100"/>
         <enumeration value="2101"/>
         <enumeration value="2102"/>
         <enumeration value="2103"/>
         <enumeration value="2104"/>
         <enumeration value="2105"/>
         <enumeration value="2106"/>
         <enumeration value="2200"/>
         <enumeration value="2201"/>
         <enumeration value="2202"/>
         <enumeration value="2300"/>
         <enumeration value="2301"/>
         <enumeration value="2302"/>
         <enumeration value="2303"/>
         <enumeration value="2304"/>
         <enumeration value="2305"/>
         <enumeration value="2306"/>
         <enumeration value="2307"/>
         <enumeration value="2308"/>
         <enumeration value="2400"/>
         <enumeration value="2500"/>
         <enumeration value="2501"/>
         <enumeration value="2502"/>
       </restriction>
     </simpleType>

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

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   END

4.2.  Shared Structure Schema

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

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

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

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

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

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

     <simpleType name="reasonBaseType">

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

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

   <!--
   DNS label type.
   -->
     <simpleType name="labelType">
       <restriction base="token">
         <minLength value="1"/>
         <maxLength value="255"/>
       </restriction>
     </simpleType>

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

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

   <!--
   Transfer status identifiers.
   -->
     <simpleType name="trStatusType">

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

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

5.  Internationalization Considerations

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

   EPP includes a provision for returning a human-readable message with
   every result code.  This document describes result codes in English,
   but the actual text returned with a result MAY be provided in a
   language negotiated when a session is established.  Languages other
   than English MUST be noted through specification of a "lang"
   attribute for each message.  Valid values for the "lang" attribute
   and "lang" negotiation elements are described in [RFC3066].

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

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6.  IANA Considerations

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

   Registration request for the EPP namespace:

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

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

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

   Registration request for the EPP XML schema:

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

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

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

   Registration request for the EPP shared structure namespace:

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

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

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

   Registration request for the EPP shared structure XML schema:

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

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

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

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7.  Security Considerations

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

  EPP uses a variant of the PLAIN SASL mechanism described in [RFC2595]
   to provide a simple application-layer authentication service that
   augments or supplements authentication and identification services
   that might be available at other protocol layers.  Where the PLAIN
   SASL mechanism specifies provision of an authorization identifier,
   authentication identifier, and password as a single string separated
   by ASCII NUL characters, EPP specifies use of a combined
   authorization and authentication identifier and a password provided
   as distinct XML elements.

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

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

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

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8.  Acknowledgements

   This document was originally written as an individual submission
   Internet-Draft.  The PROVREG working group later adopted it as a
   working group document and provided many invaluable comments and
   suggested improvements. The author wishes to acknowledge the efforts
   of WG chairs Edward Lewis and Jaap Akkerhuis for their process and
   editorial contributions.

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

9.  References

9.1.  Normative References

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

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

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

   [RFC3066]  Alvestrand, H., "Tags for the Identification of
              Languages", RFC 3066, January 2001.

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

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

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

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RFC 4930                          EPP                          May 2007

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

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

9.2.  Informative References

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

   [RFC2595]  Newman, C., "Using TLS with IMAP, POP3 and ACAP",
              RFC 2595, June 1999.

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

   [RFC2821]  Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
              April 2001.

   [RFC2960]  Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
              Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
              Zhang, L., and V. Paxson, "Stream Control Transmission
              Protocol", RFC 2960, October 2000.

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

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

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

   [RFC3730]  Hollenbeck, S., "Extensible Provisioning Protocol (EPP)",
              RFC 3730, March 2004.

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RFC 4930                          EPP                          May 2007

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

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Appendix A.  Object Mapping Template

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

   1. Introduction

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

   2. Object Attributes

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

   3. EPP Command Mapping

   3.1.  EPP Query Commands

   3.1.1.  EPP <check> Command

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

   3.1.2.  EPP <info> Command

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

   3.1.3.  EPP <poll> Command

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

   3.1.4.  EPP <transfer> Command

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

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   3.2.  EPP Transform Commands

   3.2.1.  EPP <create> Command

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

   3.2.2.  EPP <delete> Command

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

   3.2.3.  EPP <renew> Command

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

   3.2.4.  EPP <transfer> Command

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

   3.2.4.  EPP <update> Command

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

   4. Formal Syntax

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

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

   MIME media type name: application

   MIME subtype name: epp+xml

   Required parameters: none

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

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

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

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

   Published specification: This document.

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

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

   Magic number(s): None.

   File extension(s): .xml

   Macintosh file type code(s): "TEXT"

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

   Intended usage: COMMON

   Author/Change controller: IETF

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Appendix C.  Changes from RFC 3730

   1.   Minor reformatting as a result of converting I-D source format
        from nroff to XML.

   2.   Updated the state diagram in Section 2 to note that a <hello>
        can be received and processed at any time that a server is
        waiting for a command.  The text correctly describes how this
        works, but the state diagram was inconsistent with the text.

   3.   In Section 2, changed "The specific strings used to associate
       URIs and namespaces (such as the string "foo" in "xmlns:foo") in
       EPP are illustrative and are not needed for interoperability" to
       "The XML namespace prefixes used in examples (such as the string
        "foo" in "xmlns:foo") are solely for illustrative purposes.  A
        conforming implementation MUST NOT require the use of these or
        any other specific namespace prefixes".

   4.   Removed the last paragraph from Section 2 that described an
        error in the W3C XML reference specification.  This was
        corrected in a later edition.  References in this specification
        have been updated to cite the most current version.  Preserved
        the last sentence by appending it to the end of the previous
        paragraph.

   5.  Updated the description of the <value> element in Section 2.6 to
        add "or other information" to "a client-provided element
        (including XML tag and value)".

   6.   Changed text in Section 2.9.2.3 from this:

       "Service messages MUST be created for all clients affected by an
        action on an object.  For example, <transfer> actions MUST be
       reported to both the client that requests an object transfer and
        the client that has the authority to approve or reject the
        transfer request."

        to this:

       "Service messages SHOULD be created for passive clients affected
        by an action on an object. Service messages MAY also be created
        for active clients that request an action on an object, though
        such messages MUST NOT replace the normal protocol response to
        the request. For example, <transfer> actions SHOULD be reported
        to the client that has the authority to approve or reject a
        transfer request.  Other methods of server-client action
        notification, such as offline reporting, are also possible and
        are beyond the scope of this specification."

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   7.   Changed text in Section 2.9.2.3 from this:

        "A <poll> acknowledgement response notes the number of messages
        remaining in the queue and the ID of the next message available
        for retrieval."

        to this:

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

        Fixed the example to note the correct message ID. This was done
        because the msgID isn't needed to retrieve a message, only to
        ack and dequeue it, so it doesn't need to be returned in the
        response.  Implementations are known to implement this feature
        as updated.

   8.   Changed text in Section 2.9.3.4 from this:

        "Once a transfer request has been received by the server, the
        server MUST notify the current sponsoring client of the
        requested transfer by queuing a service message for retrieval
        via the <poll> command."

        to this:

        "Once a transfer request has been received by the server, the
        server MUST notify the current sponsoring client of the
        requested transfer either by queuing a service message for
        retrieval via the <poll> command or by using an out-of-band
        mechanism to inform the client of the request."

   9.   Updated Security Considerations to note implemented required
        practices for authentication and replay protection.

   10.  Updated XML references.  Updated reference from RFC 2279 to RFC
        3629.

   11.  Removed text describing use of the XML Schema schemaLocation
        attribute.  This is an optional attribute that doesn't need to
        be mandated for use in EPP.

   12. Moved RFCs 2781 and 3375 (Informational RFCs) from the normative
        reference section to the informative reference section.

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   13.  Moved RFC 3023 from the normative reference section to the
        informative reference section.  This reference is used only in
        an informative appendix.

   14. Removed references to RFC 3339 and replaced them with references
        to the W3C XML Schema specification.

Author's Address

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

   EMail: shollenbeck@verisign.com

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RFC 4930                          EPP                          May 2007

Full Copyright Statement

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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.

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