



Internet Engineering Task Force (IETF)               J. Schönwälder, Ed.
Request for Comments: 9911                        Constructor University
Obsoletes: 6991                                            December 2025
Category: Standards Track                                               
ISSN: 2070-1721


                         Common YANG Data Types

Abstract

   This document defines a collection of common data types to be used
   with the YANG data modeling language.  It includes several new type
   definitions and obsoletes RFC 6991.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9911.

Copyright Notice

   Copyright (c) 2025 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Revised BSD License text as described in Section 4.e of the
   Trust Legal Provisions and are provided without warranty as described
   in the Revised BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction
   2.  Overview
   3.  Core YANG Types
   4.  Internet Protocol Suite Types
   5.  IANA Considerations
   6.  Security Considerations
   7.  References
     7.1.  Normative References
     7.2.  Informative References
   Acknowledgments
   Author's Address

1.  Introduction

   YANG [RFC7950] is a data modeling language used to model
   configuration and state data manipulated by the Network Configuration
   Protocol (NETCONF) [RFC6241].  The YANG language supports a small set
   of built-in data types and provides mechanisms to derive other types
   from the built-in types.

   This document defines a collection of common data types.  The
   definitions are organized into two YANG modules:

   *  The "ietf-yang-types" module defines generally useful data types
      such as types for counters and gauges, types related to date and
      time, and types for common string values (e.g., UUIDs, dotted-quad
      notation, and language tags).

   *  The "ietf-inet-types" module defines data types relevant for the
      Internet Protocol suite such as types related to IP addresses,
      types for domain name, host name, URI, and email, and types for
      values in common protocol fields (e.g., port numbers).

   The initial version of these YANG modules was published as [RFC6021].
   The first revision of [RFC6021], published as [RFC6991], added
   several type definitions to the YANG modules.  This second revision
   adds further new type definitions and addresses Erratum IDs 4076
   [Err4076] and 5105 [Err5105].  Furthermore, the yang-identifier
   definition has been aligned with YANG 1.1 [RFC7950], and some pattern
   statements have been improved.  For further details, see the revision
   statements of the YANG modules in Sections 3 and 4.  A brief overview
   of all types and when they were introduced can be found in Section 2.
   Additional type definitions may be added in the future by submitting
   proposals to the NETMOD Working Group.

   This document uses the YANG terminology defined in Section 3 of
   [RFC7950].

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

2.  Overview

   Tables 1 and 2 list the types defined in the YANG modules "ietf-yang-
   types" and "ietf-inet-types".  For each type, the name of the type,
   the base type it was derived from, and the RFC introducing the type
   is listed.

       +=======================+===================+===============+
       | Type                  | Base Type         | Introduced in |
       +=======================+===================+===============+
       | counter32             | uint32            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | zero-based-counter32  | uint32            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | counter64             | uint64            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | zero-based-counter64  | uint64            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | gauge32               | uint32            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | gauge64               | uint64            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | object-identifier     | string            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | object-identifier-128 | object-identifier | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | date-and-time         | string            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | date                  | string            | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | date-no-zone          | string            | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | time                  | string            | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | time-no-zone          | string            | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | hours32               | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | minutes32             | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | seconds32             | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | centiseconds32        | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | milliseconds32        | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | microseconds32        | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | microseconds64        | int64             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | nanoseconds32         | int32             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | nanoseconds64         | int64             | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | timeticks             | int32             | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | timestamp             | timeticks         | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | phys-address          | string            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | mac-address           | string            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | xpath1.0              | string            | RFC 6021      |
       +-----------------------+-------------------+---------------+
       | hex-string            | string            | RFC 6991      |
       +-----------------------+-------------------+---------------+
       | uuid                  | string            | RFC 6991      |
       +-----------------------+-------------------+---------------+
       | dotted-quad           | string            | RFC 6991      |
       +-----------------------+-------------------+---------------+
       | language-tag          | string            | RFC 9911      |
       +-----------------------+-------------------+---------------+
       | yang-identifier       | string            | RFC 6991      |
       +-----------------------+-------------------+---------------+

           Table 1: Types Defined in the "ietf-yang-types" Module

     +=============================+=================+===============+
     | Type                        | Base Type       | Introduced in |
     +=============================+=================+===============+
     | ip-version                  | enum            | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | dscp                        | uint8           | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ipv6-flow-label             | uint32          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | port-number                 | uint16          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | protocol-number             | uint8           | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | upper-layer-protocol-number | protocol-number | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | as-number                   | uint32          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ip-address                  | union           | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ipv4-address                | string          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ipv6-address                | string          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ip-address-no-zone          | union           | RFC 6991      |
     +-----------------------------+-----------------+---------------+
     | ipv4-address-no-zone        | ipv4-address    | RFC 6991      |
     +-----------------------------+-----------------+---------------+
     | ipv6-address-no-zone        | ipv6-address    | RFC 6991      |
     +-----------------------------+-----------------+---------------+
     | ip-address-link-local       | union           | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | ipv4-address-link-local     | ipv4-address    | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | ipv6-address-link-local     | ipv6-address    | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | ip-prefix                   | union           | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ipv4-prefix                 | string          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ipv6-prefix                 | string          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | ip-address-and-prefix       | union           | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | ipv4-address-and-prefix     | string          | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | ipv6-address-and-prefix     | string          | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | domain-name                 | string          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | host-name                   | domain-name     | RFC 9911      |
     +-----------------------------+-----------------+---------------+
     | host                        | union           | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | uri                         | string          | RFC 6021      |
     +-----------------------------+-----------------+---------------+
     | email-address               | string          | RFC 9911      |
     +-----------------------------+-----------------+---------------+

           Table 2: Types Defined in the "ietf-inet-types" Module

   Some types have an equivalent Structure of Management Information
   Version 2 (SMIv2) [RFC2578] [RFC2579] data type.  A YANG data type is
   equivalent to an SMIv2 data type if the data types have the same set
   of values and the semantics of the values are equivalent.

   Table 3 lists the types defined in the "ietf-yang-types" YANG module
   with their corresponding SMIv2 types, and Table 4 lists the types
   defined in the "ietf-inet-types" module with their corresponding
   SMIv2 types.

        +=======================+================================+
        | YANG type             | Equivalent SMIv2 type (module) |
        +=======================+================================+
        | counter32             | Counter32 (SNMPv2-SMI)         |
        +-----------------------+--------------------------------+
        | zero-based-counter32  | ZeroBasedCounter32 (RMON2-MIB) |
        +-----------------------+--------------------------------+
        | counter64             | Counter64 (SNMPv2-SMI)         |
        +-----------------------+--------------------------------+
        | zero-based-counter64  | ZeroBasedCounter64 (HCNUM-TC)  |
        +-----------------------+--------------------------------+
        | gauge32               | Gauge32 (SNMPv2-SMI)           |
        +-----------------------+--------------------------------+
        | gauge64               | CounterBasedGauge64 (HCNUM-TC) |
        +-----------------------+--------------------------------+
        | object-identifier-128 | OBJECT IDENTIFIER              |
        +-----------------------+--------------------------------+
        | centiseconds32        | TimeInterval (SNMPv2-TC)       |
        +-----------------------+--------------------------------+
        | timeticks             | TimeTicks (SNMPv2-SMI)         |
        +-----------------------+--------------------------------+
        | timestamp             | TimeStamp (SNMPv2-TC)          |
        +-----------------------+--------------------------------+
        | phys-address          | PhysAddress (SNMPv2-TC)        |
        +-----------------------+--------------------------------+
        | mac-address           | MacAddress (SNMPv2-TC)         |
        +-----------------------+--------------------------------+
        | language-tag          | LangTag (LANGTAG-TC-MIB)       |
        +-----------------------+--------------------------------+

           Table 3: Equivalent SMIv2 Types for the "ietf-yang-
                              types" Module

    +=================+===============================================+
    | YANG type       | Equivalent SMIv2 type (module)                |
    +=================+===============================================+
    | ip-version      | InetVersion (INET-ADDRESS-MIB)                |
    +-----------------+-----------------------------------------------+
    | dscp            | Dscp (DIFFSERV-DSCP-TC)                       |
    +-----------------+-----------------------------------------------+
    | ipv6-flow-label | IPv6FlowLabel (IPV6-FLOW-LABEL-MIB)           |
    +-----------------+-----------------------------------------------+
    | port-number     | InetPortNumber (INET-ADDRESS-MIB)             |
    +-----------------+-----------------------------------------------+
    | as-number       | InetAutonomousSystemNumber (INET-ADDRESS-MIB) |
    +-----------------+-----------------------------------------------+
    | uri             | Uri (URI-TC-MIB)                              |
    +-----------------+-----------------------------------------------+

      Table 4: Equivalent SMIv2 Types for the "ietf-inet-types" Module

3.  Core YANG Types

   The "ietf-yang-types" YANG module references [IEEE-802-2024],
   [ISO-8601], [ISO-9834-1], [RFC2578], [RFC2579], [RFC2856], [RFC3339],
   [RFC4502], [RFC5131], [RFC5646], [RFC7950], [RFC9557], [RFC9562],
   [XPATH], and [XSD-TYPES].

   <CODE BEGINS> file "ietf-yang-types@2025-12-22.yang"
   module ietf-yang-types {
     namespace "urn:ietf:params:xml:ns:yang:ietf-yang-types";
     prefix yang;

     organization
       "IETF Network Modeling (NETMOD) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/netmod/>
        WG List:  <mailto:netmod@ietf.org>

        Editor:   Jürgen Schönwälder
                  <mailto:jschoenwaelder@constructor.university>";
     description
       "This module contains a collection of generally useful derived
        YANG data types.

        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
        'MAY', and 'OPTIONAL' in this document are to be interpreted as
        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.

        Copyright (c) 2025 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Revised BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC 9911;
        see the RFC itself for full legal notices.";

     revision 2025-12-22 {
       description
         "This revision adds the following new data types:
          - yang:date
          - yang:date-no-zone
          - yang:time
          - yang:time-no-zone
          - yang:hours32
          - yang:minutes32
          - yang:seconds32
          - yang:centiseconds32
          - yang:milliseconds32
          - yang:microseconds32
          - yang:microseconds64
          - yang:nanoseconds32
          - yang:nanoseconds64
          - yang:language-tag
          The yang-identifier definition has been aligned with YANG
          1.1, and types representing time support the representation
          of leap seconds.  The representation of time zone offsets
          has been aligned with RFC 9557.  Several description and
          pattern statements have been improved.";
       reference
         "RFC 9911: Common YANG Data Types";
     }
     revision 2013-07-15 {
       description
         "This revision adds the following new data types:
          - yang:yang-identifier
          - yang:hex-string
          - yang:uuid
          - yang:dotted-quad";
       reference
         "RFC 6991: Common YANG Data Types";
     }
     revision 2010-09-24 {
       description
         "Initial revision.";
       reference
         "RFC 6021: Common YANG Data Types";
     }

     /*** collection of counter and gauge types ***/

     typedef counter32 {
       type uint32;
       description
         "The counter32 type represents a non-negative integer
          that monotonically increases until it reaches a
          maximum value of 2^32-1 (4294967295 decimal), when it
          wraps around and starts increasing again from zero.

          Counters have no defined 'initial' value, and thus, a
          single value of a counter has (in general) no information
          content.  Discontinuities in the monotonically increasing
          value normally occur at re-initialization of the
          management system and at other times as specified in the
          description of a schema node using this type.  If
          discontinuities occur at times other than re-initialization
          (for example, at the instantiation of a schema node of type
          counter32), then a corresponding schema node should be
          defined, with an appropriate type, to indicate the last
          discontinuity.

          The counter32 type should not be used for configuration
          schema nodes.  A default statement SHOULD NOT be used in
          combination with the type counter32.

          In the value set and its semantics, this type is equivalent
          to the Counter32 type of the SMIv2.";
       reference
         "RFC 2578: Structure of Management Information Version 2
                    (SMIv2)";
     }

     typedef zero-based-counter32 {
       type counter32;
       default "0";
       description
         "The zero-based-counter32 type represents a counter32
          that has the defined 'initial' value zero.

          A data tree node using this type will be set to zero (0)
          on creation and will thereafter increase monotonically until
          it reaches a maximum value of 2^32-1 (4294967295 decimal),
          when it wraps around and starts increasing again from zero.

          Provided that an application discovers a new data tree node
          using this type within the minimum time to wrap, it can use
          the 'initial' value as a delta.  It is important for a
          management station to be aware of this minimum time and the
          actual time between polls, and to discard data if the actual
          time is too long or there is no defined minimum time.

          In the value set and its semantics, this type is equivalent
          to the ZeroBasedCounter32 textual convention of the SMIv2.";
       reference
         "RFC 4502: Remote Network Monitoring Management Information
                    Base Version 2";
     }

     typedef counter64 {
       type uint64;
       description
         "The counter64 type represents a non-negative integer
          that monotonically increases until it reaches a
          maximum value of 2^64-1 (18446744073709551615 decimal),
          when it wraps around and starts increasing again from zero.

          Counters have no defined 'initial' value, and thus, a
          single value of a counter has (in general) no information
          content.  Discontinuities in the monotonically increasing
          value normally occur at re-initialization of the
          management system and at other times as specified in the
          description of a schema node using this type.  If
          discontinuities occur at times other than re-initialization
          (for example, at the instantiation of a schema node of type
          counter64), then a corresponding schema node should be
          defined, with an appropriate type, to indicate the last
          discontinuity.

          The counter64 type should not be used for configuration
          schema nodes.  A default statement SHOULD NOT be used in
          combination with the type counter64.

          In the value set and its semantics, this type is equivalent
          to the Counter64 type of the SMIv2.";
       reference
         "RFC 2578: Structure of Management Information Version 2
                    (SMIv2)";
     }

     typedef zero-based-counter64 {
       type counter64;
       default "0";
       description
         "The zero-based-counter64 type represents a counter64 that
          has the defined 'initial' value zero.

          A data tree node using this type will be set to zero (0)
          on creation and will thereafter increase monotonically until
          it reaches a maximum value of 2^64-1 (18446744073709551615
          decimal), when it wraps around and starts increasing again
          from zero.

          Provided that an application discovers a new data tree node
          using this type within the minimum time to wrap, it can use
          the 'initial' value as a delta.  It is important for a
          management station to be aware of this minimum time and the
          actual time between polls, and to discard data if the actual
          time is too long or there is no defined minimum time.

          In the value set and its semantics, this type is equivalent
          to the ZeroBasedCounter64 textual convention of the SMIv2.";
       reference
         "RFC 2856: Textual Conventions for Additional High Capacity
                    Data Types";
     }

     typedef gauge32 {
       type uint32;
       description
         "The gauge32 type represents a non-negative integer, which
          may increase or decrease, but shall never exceed a maximum
          value, nor fall below a minimum value.  The maximum value
          cannot be greater than 2^32-1 (4294967295 decimal), and
          the minimum value cannot be smaller than 0.  The value of
          a gauge32 has its maximum value whenever the information
          being modeled is greater than or equal to its maximum
          value, and has its minimum value whenever the information
          being modeled is smaller than or equal to its minimum value.
          If the information being modeled subsequently decreases below
          the maximum value, the gauge32 also decreases; likewise, if
          the information increases above the minimum value, the
          gauge32 also increases.

          In the value set and its semantics, this type is equivalent
          to the Gauge32 type of the SMIv2.";
       reference
         "RFC 2578: Structure of Management Information Version 2
                    (SMIv2)";
     }

     typedef gauge64 {
       type uint64;
       description
         "The gauge64 type represents a non-negative integer, which
          may increase or decrease, but shall never exceed a maximum
          value, nor fall below a minimum value.  The maximum value
          cannot be greater than 2^64-1 (18446744073709551615), and
          the minimum value cannot be smaller than 0.  The value of
          a gauge64 has its maximum value whenever the information
          being modeled is greater than or equal to its maximum
          value, and has its minimum value whenever the information
          being modeled is smaller than or equal to its minimum value.
          If the information being modeled subsequently decreases
          below (increases above) the maximum (minimum) value, the
          gauge64 also decreases (increases).

          In the value set and its semantics, this type is equivalent
          to the CounterBasedGauge64 SMIv2 textual convention defined
          in RFC 2856";
       reference
         "RFC 2856: Textual Conventions for Additional High Capacity
                    Data Types";
     }

     /*** collection of identifier-related types ***/

     typedef object-identifier {
       type string {
         pattern '(([0-1](\.[1-3]?[0-9]))|(2\.(0|([1-9][0-9]*))))'
               + '(\.(0|([1-9][0-9]*)))*';
       }
       description
         "The object-identifier type represents administratively
          assigned names in a registration-hierarchical-name tree.

          Values of this type are denoted as a sequence of numerical
          non-negative sub-identifier values.  Each sub-identifier
          value MUST NOT exceed 2^32-1 (4294967295).  Sub-identifiers
          are separated by single dots and without any intermediate
          whitespace.

          The ASN.1 standard restricts the value space of the first
          sub-identifier to 0, 1, or 2.  Furthermore, the value space
          of the second sub-identifier is restricted to the range
          0 to 39 if the first sub-identifier is 0 or 1.  Finally,
          the ASN.1 standard requires that an object identifier
          has always at least two sub-identifiers.  The pattern
          captures these restrictions.

          Although the number of sub-identifiers is not limited,
          module designers should realize that there may be
          implementations that stick with the SMIv2 limit of 128
          sub-identifiers.

          This type is a superset of the SMIv2 OBJECT IDENTIFIER type
          since it is not restricted to 128 sub-identifiers.  Hence,
          this type SHOULD NOT be used to represent the SMIv2 OBJECT
          IDENTIFIER type; the object-identifier-128 type SHOULD be
          used instead.";
       reference
         "ISO 9834-1: Information technology -- Procedures for the
          operation of object identifier registration authorities --
          Part 1: General procedures and top arcs of the international
          object identifier tree";
     }

     typedef object-identifier-128 {
       type object-identifier {
         pattern '[0-9]*(\.[0-9]*){1,127}';
       }
       description
         "This type represents object-identifiers restricted to 128
          sub-identifiers.

          In the value set and its semantics, this type is equivalent
          to the OBJECT IDENTIFIER type of the SMIv2.";
       reference
         "RFC 2578: Structure of Management Information Version 2
                    (SMIv2)";
     }

     /*** collection of types related to date and time ***/

     typedef date-and-time {
       type string {
         pattern
           '[0-9]{4}-(1[0-2]|0[1-9])-(0[1-9]|[1-2][0-9]|3[0-1])'
         + 'T(0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)'
         + '(\.[0-9]+)?'
         + '(Z|[\+\-]((1[0-3]|0[0-9]):([0-5][0-9])|14:00))?';
       }
       description
         "The date-and-time type is a profile of the ISO 8601
          standard for representation of dates and times using the
          Gregorian calendar.  The profile is defined by the
          date-time production in Section 5.6 of RFC 3339 and the
          update defined in Section 2 of RFC 9557.  The value of
          60 for seconds is allowed only in the case of leap seconds.

          The date-and-time type is compatible with the dateTime XML
          schema dateTime type with the following notable exceptions:

          (a) The date-and-time type does not allow negative years.

          (b) The time-offset Z indicates that the date-and-time
              value is reported in UTC and that the local time zone
              reference point is unknown.  The time-offset +00:00
              indicates that the date-and-time value is reported in
              UTC and that the local time zone reference point is UTC
              (see Section 2 of RFC 9557).

          This type is not equivalent to the DateAndTime textual
          convention of the SMIv2 since RFC 3339 uses a different
          separator between full-date and full-time and provides
          higher resolution of time-secfrac.

          The canonical format for date-and-time values with a known
          time zone uses a numeric time zone offset that is calculated
          using the device's configured known offset to UTC time.  A
          change of the device's offset to UTC time will cause
          date-and-time values to change accordingly.  Such changes
          might happen periodically if a server automatically follows
          daylight saving time (DST) time zone offset changes.  The
          canonical format for date-and-time values reported in UTC
          with an unknown local time zone offset SHOULD use the
          time-offset Z and MAY use -00:00 for backwards
          compatibility.";
       reference
         "ISO 8601: Data elements and interchange formats -- Information
                    interchange -- Representation of dates and times
          RFC 3339: Date and Time on the Internet: Timestamps
          RFC 9557: Date and Time on the Internet: Timestamps
                    with Additional Information
          RFC 2579: Textual Conventions for SMIv2
          XSD-TYPES: XML Schema Definition Language (XSD) 1.1
                     Part 2: Datatypes";
     }

     typedef date {
       type string {
         pattern '[0-9]{4}-(1[0-2]|0[1-9])-(0[1-9]|[1-2][0-9]|3[0-1])'
               + '(Z|[\+\-]((1[0-3]|0[0-9]):([0-5][0-9])|14:00))?';
       }
       description
         "The date type represents a time-interval of the length
          of a day, i.e., 24 hours.  It includes an optional time
          zone offset.

          The date type is compatible with the XML schema date
          type with the following notable exceptions:

          (a) The date type does not allow negative years.

          (b) The time-offset Z indicates that the date value is
              reported in UTC and that the local time zone reference
              point is unknown.  The time-offset +00:00 indicates that
              the date value is reported in UTC and that the local
              time zone reference point is UTC (see Section 2 of
              RFC 9557).

          The canonical format for date values with a known time
          zone uses a numeric time zone offset that is calculated using
          the device's configured known offset to UTC time.  A change of
          the device's offset to UTC time will cause date values
          to change accordingly.  Such changes might happen periodically
          if a server automatically follows daylight saving time
          (DST) time zone offset changes.  The canonical format for
          date values reported in UTC with an unknown local time zone
          offset uses the time-offset Z.";
       reference
         "RFC 3339: Date and Time on the Internet: Timestamps
          RFC 9557: Date and Time on the Internet: Timestamps
                    with Additional Information
          XSD-TYPES: XML Schema Definition Language (XSD) 1.1
                     Part 2: Datatypes";
     }

     typedef date-no-zone {
       type date {
         pattern '[0-9]{4}-(1[0-2]|0[1-9])-(0[1-9]|[1-2][0-9]|3[0-1])';
       }
       description
         "The date-no-zone type represents a date without the optional
          time zone offset information.";
     }

     typedef time {
       type string {
         pattern
           '(0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)'
         + '(\.[0-9]+)?'
         + '(Z|[\+\-]((1[0-3]|0[0-9]):([0-5][0-9])|14:00))?';
       }
       description
         "The time type represents an instance of time of zero duration
          that recurs every day.  It includes an optional time zone
          offset.  The value of 60 for seconds is allowed only in the
          case of leap seconds.

          The time type is compatible with the XML schema time
          type with the following notable exception:

          (a) The time-offset Z indicates that the time value is
              reported in UTC and that the local time zone reference
              point is unknown.  The time-offset +00:00 indicates that
              the time value is reported in UTC and that the local
              time zone reference point is UTC (see Section 2 of
              RFC 9557).

          The canonical format for time values with a known time
          zone uses a numeric time zone offset that is calculated using
          the device's configured known offset to UTC time.  A change of
          the device's offset to UTC time will cause time values
          to change accordingly.  Such changes might happen periodically
          if a server automatically follows daylight saving time
          (DST) time zone offset changes.  The canonical format for
          time values reported in UTC with an unknown local time zone
          offset uses the time-offset Z.";
       reference
         "RFC 3339: Date and Time on the Internet: Timestamps
          RFC 9557: Date and Time on the Internet: Timestamps
                    with Additional Information
          XSD-TYPES: XML Schema Definition Language (XSD) 1.1
                     Part 2: Datatypes";
     }

     typedef time-no-zone {
       type time {
         pattern
           '(0[0-9]|1[0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)'
         + '(\.[0-9]+)?';
       }
       description
         "The time-no-zone type represents a time without the optional
          time zone offset information.";
     }

     typedef hours32 {
       type int32;
       units "hours";
       description
         "A period of time measured in units of hours.

          The maximum time period that can be expressed is in the
          range [-89478485 days 08:00:00 to 89478485 days 07:00:00].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef minutes32 {
       type int32;
       units "minutes";
       description
         "A period of time measured in units of minutes.

          The maximum time period that can be expressed is in the
          range [-1491308 days 2:08:00 to 1491308 days 2:07:00].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef seconds32 {
       type int32;
       units "seconds";
       description
         "A period of time measured in units of seconds.

          The maximum time period that can be expressed is in the
          range [-24855 days 03:14:08 to 24855 days 03:14:07].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef centiseconds32 {
       type int32;
       units "centiseconds";
       description
         "A period of time measured in units of 10^-2 seconds.

          The maximum time period that can be expressed is in the
          range [-248 days 13:13:56 to 248 days 13:13:56].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef milliseconds32 {
       type int32;
       units "milliseconds";
       description
         "A period of time measured in units of 10^-3 seconds.

          The maximum time period that can be expressed is in the
          range [-24 days 20:31:23 to 24 days 20:31:23].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef microseconds32 {
       type int32;
       units "microseconds";
       description
         "A period of time measured in units of 10^-6 seconds.

          The maximum time period that can be expressed is in the
          range [-00:35:47 to 00:35:47].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef microseconds64 {
       type int64;
       units "microseconds";
       description
         "A period of time measured in units of 10^-6 seconds.

          The maximum time period that can be expressed is in the
          range [-106751991 days 04:00:54 to 106751991 days 04:00:54].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef nanoseconds32 {
       type int32;
       units "nanoseconds";
       description
         "A period of time measured in units of 10^-9 seconds.

          The maximum time period that can be expressed is in the
          range [-00:00:02 to 00:00:02].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef nanoseconds64 {
       type int64;
       units "nanoseconds";
       description
         "A period of time measured in units of 10^-9 seconds.

          The maximum time period that can be expressed is in the
          range [-106753 days 23:12:44 to 106752 days 0:47:16].

          This type should be range-restricted in situations
          where only non-negative time periods are desirable
          (i.e., range '0..max').";
     }

     typedef timeticks {
       type uint32;
       description
         "The timeticks type represents a non-negative integer that
          represents the time, modulo 2^32 (4294967296 decimal), in
          hundredths of a second between two epochs.  When a schema
          node is defined that uses this type, the description of
          the schema node identifies both of the reference epochs.

          In the value set and its semantics, this type is equivalent
          to the TimeTicks type of the SMIv2.";
       reference
         "RFC 2578: Structure of Management Information Version 2
                    (SMIv2)";
     }

     typedef timestamp {
       type timeticks;
       description
         "The timestamp type represents the value of an associated
          timeticks schema node instance at which a specific occurrence
          happened.  The specific occurrence must be defined in the
          description of any schema node defined using this type.  When
          the specific occurrence occurred prior to the last time the
          associated timeticks schema node instance was zero, then the
          timestamp value is zero.

          Note that this requires all timestamp values to be reset to
          zero when the value of the associated timeticks schema node
          instance reaches 497+ days and wraps around to zero.

          The associated timeticks schema node must be specified
          in the description of any schema node using this type.

          In the value set and its semantics, this type is equivalent
          to the TimeStamp textual convention of the SMIv2.";
       reference
         "RFC 2579: Textual Conventions for SMIv2";
     }

     /*** collection of generic address types ***/

     typedef phys-address {
       type string {
         pattern '([0-9a-fA-F]{2}(:[0-9a-fA-F]{2})*)?';
       }
       description
         "Represents media- or physical-level addresses represented
          as a sequence of octets, each octet represented by two
          hexadecimal numbers.  Octets are separated by colons.  The
          canonical representation uses lowercase characters.

          In the value set and its semantics, this type is equivalent
          to the PhysAddress textual convention of the SMIv2.";
       reference
         "RFC 2579: Textual Conventions for SMIv2";
     }

     typedef mac-address {
       type string {
         pattern '[0-9a-fA-F]{2}(:[0-9a-fA-F]{2}){5}';
       }
       description
         "The mac-address type represents a 48-bit IEEE 802 Media
          Access Control (MAC) address.  The canonical representation
          uses lowercase characters.  Note that there are IEEE 802 MAC
          addresses with a different length that this type cannot
          represent.  The phys-address type may be used to represent
          physical addresses of varying length.

          In the value set and its semantics, this type is equivalent
          to the MacAddress textual convention of the SMIv2.";
       reference
         "IEEE 802: IEEE Standard for Local and Metropolitan Area
                    Networks: Overview and Architecture
          RFC 2579: Textual Conventions for SMIv2";
     }

     /*** collection of XML-specific types ***/

     typedef xpath1.0 {
       type string;
       description
         "This type represents an XPATH 1.0 expression.

          When a schema node is defined that uses this type, the
          description of the schema node MUST specify the XPath
          context in which the XPath expression is evaluated.";
       reference
         "XPATH: XML Path Language (XPath) Version 1.0";
     }

     /*** collection of string types ***/

     typedef hex-string {
       type string {
         pattern '([0-9a-fA-F]{2}(:[0-9a-fA-F]{2})*)?';
       }
       description
         "A hexadecimal string with octets represented as hex digits
          separated by colons.  The canonical representation uses
          lowercase characters.";
     }

     typedef uuid {
       type string {
         pattern '[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-'
               + '[0-9a-fA-F]{4}-[0-9a-fA-F]{12}';
       }
       description
         "A Universally Unique IDentifier in the string representation
          defined in RFC 9562.  The canonical representation uses
          lowercase characters.

          The following is an example of a UUID in string
          representation:
          f81d4fae-7dec-11d0-a765-00a0c91e6bf6.
         ";
       reference
         "RFC 9562: Universally Unique IDentifiers (UUIDs)";
     }

     typedef dotted-quad {
       type string {
         pattern
           '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
         + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])';
       }
       description
         "An unsigned 32-bit number expressed in the dotted-quad
          notation, i.e., four octets written as decimal numbers
          and separated with the '.' (full stop) character.";
     }

     typedef language-tag {
       type string;
       description
         "A language tag according to RFC 5646 (BCP 47).  The
          canonical representation uses lowercase characters.

          Values of this type must be well-formed language tags,
          in conformance with the definition of well-formed tags
          in BCP 47.  Implementations MAY further limit the values
          they accept to those permitted by a 'validating'
          processor, as defined in BCP 47.

          The canonical representation of values of this type is
          aligned with the SMIv2 LangTag textual convention for
          language tags fitting the length constraints imposed
          by the LangTag textual convention.";
       reference
         "RFC 5646: Tags for Identifying Languages
          RFC 5131: A MIB Textual Convention for Language Tags";
     }

     /*** collection of YANG-specific types ***/

     typedef yang-identifier {
       type string {
         length "1..max";
         pattern '[a-zA-Z_][a-zA-Z0-9\-_.]*';
       }
       description
         "A YANG identifier string as defined by the 'identifier'
          rule in Section 14 of RFC 7950.  An identifier must
          start with an alphabetic character or an underscore
          followed by an arbitrary sequence of alphabetic or
          numeric characters, underscores, hyphens, or dots.

          This definition conforms to YANG 1.1 defined in RFC
          7950.  In RFC 6991, this definition excluded
          all identifiers starting with any possible combination
          of the lowercase or uppercase character sequence 'xml',
          as required by YANG 1 defined in RFC 6020.  If this type
          is used in a YANG 1 context, then this restriction still
          applies.";
       reference
         "RFC 7950: The YANG 1.1 Data Modeling Language
          RFC 6991: Common YANG Data Types
          RFC 6020: YANG - A Data Modeling Language for the
                    Network Configuration Protocol (NETCONF)";
     }
   }
   <CODE ENDS>

4.  Internet Protocol Suite Types

   The "ietf-inet-types" YANG module references [RFC0768], [RFC0791],
   [RFC0952], [RFC1034], [RFC1123], [RFC1930], [RFC2317], [RFC2474],
   [RFC2780], [RFC2782], [RFC3289], [RFC3305], [RFC3595], [RFC3927],
   [RFC3986], [RFC4001], [RFC4007], [RFC4271], [RFC4291], [RFC4340],
   [RFC4592], [RFC5017], [RFC5322], [RFC5890], [RFC5952], [RFC6532],
   [RFC6793], [RFC8200], [RFC9260], [RFC9293], and [RFC9499].

   <CODE BEGINS> file "ietf-inet-types@2025-12-22.yang"
   module ietf-inet-types {
     namespace "urn:ietf:params:xml:ns:yang:ietf-inet-types";
     prefix inet;

     organization
       "IETF Network Modeling (NETMOD) Working Group";
     contact
       "WG Web:   <https://datatracker.ietf.org/wg/netmod/>
        WG List:  <mailto:netmod@ietf.org>

        Editor:   Jürgen Schönwälder
                  <mailto:jschoenwaelder@constructor.university>";
     description
       "This module contains a collection of generally useful derived
        YANG data types for Internet addresses and related things.

        The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
        NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
        'MAY', and 'OPTIONAL' in this document are to be interpreted as
        described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.

        Copyright (c) 2025 IETF Trust and the persons identified as
        authors of the code.  All rights reserved.

        Redistribution and use in source and binary forms, with or
        without modification, is permitted pursuant to, and subject
        to the license terms contained in, the Revised BSD License
        set forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC 9911;
        see the RFC itself for full legal notices.";

     revision 2025-12-22 {
       description
         "This revision adds the following new data types:
          - inet:ip-address-and-prefix
          - inet:ipv4-address-and-prefix
          - inet:ipv6-address-and-prefix
          - inet:protocol-number
          - inet:upper-layer-protocol-number
          - inet:host-name
          - inet:email-address
          - inet:ip-address-link-local
          - inet:ipv4-address-link-local
          - inet:ipv6-address-link-local
          The inet:host union was changed to use inet:host-name instead
          of inet:domain-name.  Several pattern statements have been
          improved.";
       reference
         "RFC 9911: Common YANG Data Types";
     }
     revision 2013-07-15 {
       description
         "This revision adds the following new data types:
          - inet:ip-address-no-zone
          - inet:ipv4-address-no-zone
          - inet:ipv6-address-no-zone";
       reference
         "RFC 6991: Common YANG Data Types";
     }
     revision 2010-09-24 {
       description
         "Initial revision.";
       reference
         "RFC 6021: Common YANG Data Types";
     }

     /*** collection of types related to protocol fields ***/

     typedef ip-version {
       type enumeration {
         enum unknown {
           value 0;
           description
             "An unknown or unspecified version of the Internet
              Protocol.";
         }
         enum ipv4 {
           value 1;
           description
             "The IPv4 protocol as defined in RFC 791.";
         }
         enum ipv6 {
           value 2;
           description
             "The IPv6 protocol as defined in RFC 8200.";
         }
       }
       description
         "This value represents the version of the Internet Protocol.

          In the value set and its semantics, this type is equivalent
          to the InetVersion textual convention of the SMIv2.";
       reference
         "RFC  791: Internet Protocol
          RFC 8200: Internet Protocol, Version 6 (IPv6) Specification
          RFC 4001: Textual Conventions for Internet Network Addresses";
     }

     typedef dscp {
       type uint8 {
         range "0..63";
       }
       description
         "The dscp type represents a Differentiated Services Code Point
          that may be used for marking packets in a traffic stream.

          In the value set and its semantics, this type is equivalent
          to the Dscp textual convention of the SMIv2.";
       reference
         "RFC 3289: Management Information Base for the Differentiated
                    Services Architecture
          RFC 2474: Definition of the Differentiated Services Field
                    (DS Field) in the IPv4 and IPv6 Headers
          RFC 2780: IANA Allocation Guidelines For Values In
                    the Internet Protocol and Related Headers";
     }

     typedef ipv6-flow-label {
       type uint32 {
         range "0..1048575";
       }
       description
         "The ipv6-flow-label type represents the flow identifier or
          Flow Label in an IPv6 packet header that may be used to
          discriminate traffic flows.

          In the value set and its semantics, this type is equivalent
          to the IPv6FlowLabel textual convention of the SMIv2.";
       reference
         "RFC 3595: Textual Conventions for IPv6 Flow Label
          RFC 8200: Internet Protocol, Version 6 (IPv6) Specification";
     }

     typedef port-number {
       type uint16 {
         range "0..65535";
       }
       description
         "The port-number type represents a 16-bit port number of an
          Internet transport-layer protocol such as UDP, TCP, DCCP, or
          SCTP.

          Port numbers are assigned by IANA.  The current list of
          all assignments is available from <https://www.iana.org/>.

          Note that the port number value zero is reserved by IANA.  In
          situations where the value zero does not make sense, it can
          be excluded by subtyping the port-number type.

          In the value set and its semantics, this type is equivalent
          to the InetPortNumber textual convention of the SMIv2.";
       reference
         "RFC  768: User Datagram Protocol
          RFC 9293: Transmission Control Protocol (TCP)
          RFC 9260: Stream Control Transmission Protocol
          RFC 4340: Datagram Congestion Control Protocol (DCCP)
          RFC 4001: Textual Conventions for Internet Network Addresses";
     }

     typedef protocol-number {
       type uint8;
       description
         "The protocol-number type represents an 8-bit Internet
          Protocol number, carried in the 'protocol' field of the
          IPv4 header or in the 'next header' field of the IPv6
          header.

          Protocol numbers are assigned by IANA.  The current list of
          all assignments is available from <https://www.iana.org/>.";
       reference
         "RFC  791: Internet Protocol
          RFC 8200: Internet Protocol, Version 6 (IPv6) Specification";
     }

     typedef upper-layer-protocol-number {
       type protocol-number;
       description
         "The upper-layer-protocol-number represents the upper-layer
          protocol number carried in an IP packet.  For IPv6 packets
          with extension headers, this is the protocol number carried
          in the last 'next header' field of the chain of IPv6 extension
          headers.";
       reference
         "RFC  791: Internet Protocol
          RFC 8200: Internet Protocol, Version 6 (IPv6) Specification";
     }

     /*** collection of types related to autonomous systems ***/

     typedef as-number {
       type uint32;
       description
         "The as-number type represents autonomous system numbers
          that identify an Autonomous System (AS).  An AS is a set
          of routers under a single technical administration, using
          an interior gateway protocol and common metrics to route
          packets within the AS, and using an exterior gateway
          protocol to route packets to other ASes.  IANA maintains
          the autonomous system number space and has delegated large
          parts to the regional registries.

          Autonomous system numbers were originally limited to 16
          bits.  BGP extensions have enlarged the autonomous system
          number space to 32 bits.  This type therefore uses an uint32
          base type without a range restriction in order to support
          a larger autonomous system number space.

          In the value set and its semantics, this type is equivalent
          to the InetAutonomousSystemNumber textual convention of
          the SMIv2.";
       reference
         "RFC 1930: Guidelines for creation, selection, and registration
                    of an Autonomous System (AS)
          RFC 4271: A Border Gateway Protocol 4 (BGP-4)
          RFC 4001: Textual Conventions for Internet Network Addresses
          RFC 6793: BGP Support for Four-Octet Autonomous System (AS)
                    Number Space";
     }

     /*** collection of types related to IP addresses and hostnames ***/

     typedef ip-address {
       type union {
         type ipv4-address;
         type ipv6-address;
       }
       description
         "The ip-address type represents an IP address and is IP
          version neutral.  The format of the textual representation
          implies the IP version.  This type supports scoped addresses
          by allowing zone identifiers in the address format.";
       reference
         "RFC 4007: IPv6 Scoped Address Architecture";
     }

     typedef ipv4-address {
       type string {
         pattern
           '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
         + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
         + '(%.+)?';
       }
       description
         "The ipv4-address type represents an IPv4 address in
          dotted-quad notation.  The IPv4 address may include a zone
          index, separated by a % sign.  If a system uses zone names
          that are not represented in UTF-8, then an implementation
          needs to use some mechanism to transform the local name
          into UTF-8.  The definition of such a mechanism is outside
          the scope of this document.

          The zone index is used to disambiguate identical address
          values.  For link-local addresses, the zone index will
          typically be the interface index number or the name of an
          interface.  If the zone index is not present, the default
          zone of the device will be used.

          The canonical format for the zone index is the numerical
          format";
     }

     typedef ipv6-address {
       type string {
         pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
               + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
               + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
               + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
               + '(%[A-Za-z0-9][A-Za-z0-9\-\._~/]*)?';
         pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
               + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
               + '(%.+)?';
       }
       description
         "The ipv6-address type represents an IPv6 address in full,
          mixed, shortened, and shortened-mixed notation.  The IPv6
          address may include a zone index, separated by a % sign.
          If a system uses zone names that are not represented in
          UTF-8, then an implementation needs to use some mechanism
          to transform the local name into UTF-8.  The definition of
          such a mechanism is outside the scope of this document.

          The zone index is used to disambiguate identical address
          values.  For link-local addresses, the zone index will
          typically be the interface index number or the name of an
          interface.  If the zone index is not present, the default
          zone of the device will be used.

          The canonical format of IPv6 addresses uses the textual
          representation defined in Section 4 of RFC 5952.  The
          canonical format for the zone index is the numerical
          format as described in Section 11.2 of RFC 4007.";
       reference
         "RFC 4291: IP Version 6 Addressing Architecture
          RFC 4007: IPv6 Scoped Address Architecture
          RFC 5952: A Recommendation for IPv6 Address Text
                    Representation";
     }

     typedef ip-address-no-zone {
       type union {
         type ipv4-address-no-zone;
         type ipv6-address-no-zone;
       }
       description
         "The ip-address-no-zone type represents an IP address and is
          IP version neutral.  The format of the textual representation
          implies the IP version.  This type does not support scoped
          addresses since it does not allow zone identifiers in the
          address format.";
       reference
         "RFC 4007: IPv6 Scoped Address Architecture";
     }

     typedef ipv4-address-no-zone {
       type ipv4-address {
         pattern '[0-9\.]*';
       }
       description
         "An IPv4 address without a zone index.  This type, derived
          from the type ipv4-address, may be used in situations where
          the zone is known from the context and no zone index is
          needed.";
     }

     typedef ipv6-address-no-zone {
       type ipv6-address {
         pattern '[0-9a-fA-F:\.]*';
       }
       description
         "An IPv6 address without a zone index.  This type, derived
          from the type ipv6-address, may be used in situations where
          the zone is known from the context and no zone index is
          needed.";
       reference
         "RFC 4291: IP Version 6 Addressing Architecture
          RFC 4007: IPv6 Scoped Address Architecture
          RFC 5952: A Recommendation for IPv6 Address Text
                    Representation";
     }

     typedef ip-address-link-local {
       type union {
         type ipv4-address-link-local;
         type ipv6-address-link-local;
       }
       description
         "The ip-address-link-local type represents a link-local IP
          address and is IP version neutral.  The format of the textual
          representation implies the IP version.";
     }

     typedef ipv4-address-link-local {
       type ipv4-address {
         pattern '169\.254\..*';
       }
       description
         "The ipv4-address-link-local type represents a link-local IPv4
          address in the prefix 169.254.0.0/16 as defined in Section 2.1
          of RFC 3927.";
       reference
         "RFC 3927: Dynamic Configuration of IPv4 Link-Local Addresses";
     }

     typedef ipv6-address-link-local {
       type ipv6-address {
         pattern '[fF][eE][89aAbB][0-9a-fA-F]:.*';
       }
       description
         "The ipv6-address-link-local type represents a link-local IPv6
          address in the prefix fe80::/10 as defined in Section 2.4 of
          RFC 4291.";
       reference
         "RFC 4291: IP Version 6 Addressing Architecture";
     }

     typedef ip-prefix {
       type union {
         type ipv4-prefix;
         type ipv6-prefix;
       }
       description
         "The ip-prefix type represents an IP prefix and is IP
          version neutral.  The format of the textual representations
          implies the IP version.";
     }

     typedef ipv4-prefix {
       type string {
         pattern
           '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
         + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
         + '/(([0-9])|([1-2][0-9])|(3[0-2]))';
       }
       description
         "The ipv4-prefix type represents an IPv4 prefix.
          The prefix length is given by the number following the
          slash character and must be less than or equal to 32.

          A prefix length value of n corresponds to an IP address
          mask that has n contiguous 1-bits from the most
          significant bit (MSB) and all other bits set to 0.

          The canonical format of an IPv4 prefix has all bits of
          the IPv4 address set to zero that are not part of the
          IPv4 prefix.

          The definition of ipv4-prefix does not require that bits
          that are not part of the prefix be set to zero.  However,
          implementations have to return values in canonical format,
          which requires non-prefix bits to be set to zero.  This means
          that 192.0.2.1/24 must be accepted as a valid value, but it
          will be converted into the canonical format 192.0.2.0/24.";
     }

     typedef ipv6-prefix {
       type string {
         pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
               + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
               + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
               + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
               + '(/(([0-9])|([0-9]{2})|(1[0-1][0-9])|(12[0-8])))';
         pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
               + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
               + '(/.+)';
       }
       description
         "The ipv6-prefix type represents an IPv6 prefix.
          The prefix length is given by the number following the
          slash character and must be less than or equal to 128.

          A prefix length value of n corresponds to an IP address
          mask that has n contiguous 1-bits from the most
          significant bit (MSB) and all other bits set to 0.

          The canonical format of an IPv6 prefix has all bits of
          the IPv6 address set to zero that are not part of the
          IPv6 prefix.  Furthermore, the IPv6 address is represented
          as defined in Section 4 of RFC 5952.

          The definition of ipv6-prefix does not require that bits
          that are not part of the prefix be set to zero.  However,
          implementations have to return values in canonical format,
          which requires non-prefix bits to be set to zero.  This means
          that 2001:db8::1/64 must be accepted as a valid value, but it
          will be converted into the canonical format 2001:db8::/64.";
       reference
         "RFC 5952: A Recommendation for IPv6 Address Text
                    Representation";
     }

     typedef ip-address-and-prefix {
       type union {
         type ipv4-address-and-prefix;
         type ipv6-address-and-prefix;
       }
       description
         "The ip-address-and-prefix type represents an IP address and
          prefix and is IP version neutral.  The format of the textual
          representations implies the IP version.";
     }

     typedef ipv4-address-and-prefix {
       type string {
         pattern
           '(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}'
         + '([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])'
         + '/(([0-9])|([1-2][0-9])|(3[0-2]))';
       }
       description
         "The ipv4-address-and-prefix type represents an IPv4
          address and an associated IPv4 prefix.
          The prefix length is given by the number following the
          slash character and must be less than or equal to 32.

          A prefix length value of n corresponds to an IP address
          mask that has n contiguous 1-bits from the most
          significant bit (MSB) and all other bits set to 0.";
     }

     typedef ipv6-address-and-prefix {
       type string {
         pattern '((:|[0-9a-fA-F]{0,4}):)([0-9a-fA-F]{0,4}:){0,5}'
               + '((([0-9a-fA-F]{0,4}:)?(:|[0-9a-fA-F]{0,4}))|'
               + '(((25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])\.){3}'
               + '(25[0-5]|2[0-4][0-9]|[01]?[0-9]?[0-9])))'
               + '(/(([0-9])|([0-9]{2})|(1[0-1][0-9])|(12[0-8])))';
         pattern '(([^:]+:){6}(([^:]+:[^:]+)|(.*\..*)))|'
               + '((([^:]+:)*[^:]+)?::(([^:]+:)*[^:]+)?)'
               + '(/.+)';
       }
       description
         "The ipv6-address-and-prefix type represents an IPv6
          address and an associated IPv6 prefix.
          The prefix length is given by the number following the
          slash character and must be less than or equal to 128.

          A prefix length value of n corresponds to an IP address
          mask that has n contiguous 1-bits from the most
          significant bit (MSB) and all other bits set to 0.

          The canonical format requires that the IPv6 address is
          represented as defined in Section 4 of RFC 5952.";
       reference
         "RFC 5952: A Recommendation for IPv6 Address Text
                    Representation";
     }

     /*** collection of domain name and URI types ***/

     typedef domain-name {
       type string {
         length "1..253";
         pattern
           '((([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.)*'
         + '([a-zA-Z0-9_]([a-zA-Z0-9\-_]){0,61})?[a-zA-Z0-9]\.?)'
         + '|\.';
       }
       description
         "The domain-name type represents a DNS domain name.  The
          name SHOULD be fully qualified whenever possible.  This
          type does not support wildcards (see RFC 4592) or
          classless in-addr.arpa delegations (see RFC 2317).

          Internet domain names are only loosely specified.  Section
          3.5 of RFC 1034 recommends a syntax (modified in Section
          2.1 of RFC 1123).  The pattern above is intended to allow
          for current practice in domain name use and some possible
          future expansion.  Note that Internet host names have a
          stricter syntax (described in RFC 952) than the DNS
          recommendations in RFCs 1034 and 1123.  Schema nodes
          representing host names should use the host-name type
          instead of the domain-type.

          The encoding of DNS names in the DNS protocol is limited
          to 255 characters.  Since the encoding consists of labels
          prefixed by a length byte and there is a trailing NUL
          byte, only 253 characters can appear in the textual dotted
          notation.

          The description clause of schema nodes using the domain-name
          type MUST describe when and how these names are resolved to
          IP addresses.  Note that the resolution of a domain-name value
          may require to query multiple DNS records (e.g., A for IPv4
          and AAAA for IPv6).  The order of the resolution process and
          which DNS record takes precedence can either be defined
          explicitly or depend on the configuration of the
          resolver.

          Domain-name values use the ASCII encoding.  Their canonical
          format uses lowercase ASCII characters.  Internationalized
          domain names MUST be A-labels as per RFC 5890.";
       reference
         "RFC  952: DoD Internet Host Table Specification
          RFC 1034: Domain Names - Concepts and Facilities
          RFC 1123: Requirements for Internet Hosts -- Application
                    and Support
          RFC 2317: Classless IN-ADDR.ARPA delegation
          RFC 2782: A DNS RR for specifying the location of services
                    (DNS SRV)
          RFC 4592: The Role of Wildcards in the Domain Name System
          RFC 5890: Internationalized Domain Names in Applications
                    (IDNA): Definitions and Document Framework
          RFC 9499: DNS Terminology";
     }

     typedef host-name {
       type domain-name {
         length "2..max";
         pattern '[a-zA-Z0-9\-\.]+';
       }
       description
         "The host-name type represents fully qualified host names.
          Host names must be at least two characters long (see RFC 952),
          and they are restricted to labels consisting of letters,
          digits, and hyphens separated by dots (see RFCs 1123 and
          952).";
       reference
         "RFC  952: DoD Internet Host Table Specification
          RFC 1123: Requirements for Internet Hosts -- Application
                    and Support";
     }

     typedef host {
       type union {
         type ip-address;
         type host-name;
       }
       description
         "The host type represents either an IP address or a fully
          qualified host name.";
     }

     typedef uri {
       type string {
         pattern '[a-z][a-z0-9+.-]*:.*';
       }
       description
         "The uri type represents a Uniform Resource Identifier
          (URI) as defined by the rule 'URI' in RFC 3986.

          Objects using the uri type MUST be in ASCII encoding
          and MUST be normalized as described in Sections 6.2.1,
          6.2.2.1, and 6.2.2.2 of RFC 3986.  Characters that can be
          represented without using percent-encoding are represented
          as characters (without percent-encoding), and all
          case-insensitive characters are set to lowercase except
          for hexadecimal digits within a percent-encoded triplet,
          which are normalized to uppercase as described in
          Section 6.2.2.1 of RFC 3986.

          The purpose of this normalization is to help provide
          unique URIs.  Note that this normalization is not
          sufficient to provide uniqueness.  Two URIs that are
          textually distinct after this normalization may still be
          equivalent.

          Objects using the uri type may restrict the schemes that
          they permit.  For example, 'data:' and 'urn:' schemes
          might not be appropriate.

          A zero-length URI is not a valid URI.  This can be used to
          express 'URI absent' where required.

          In the value set and its semantics, this type is equivalent
          to the Uri SMIv2 textual convention defined in RFC 5017.";
       reference
         "RFC 3986: Uniform Resource Identifier (URI): Generic Syntax
          RFC 3305: Report from the Joint W3C/IETF URI Planning Interest
                    Group: Uniform Resource Identifiers (URIs), URLs,
                    and Uniform Resource Names (URNs): Clarifications
                    and Recommendations
          RFC 5017: MIB Textual Conventions for Uniform Resource
                    Identifiers (URIs)";
     }

     typedef email-address {
       type string {
         pattern '.+@.+';
       }
       description
         "The email-address type represents an internationalized
          email address.

          The email address format is defined by the addr-spec
          ABNF rule in Section 3.4.1 of RFC 5322.  This format has
          been extended by RFC 6532 to support internationalized
          email addresses.  Implementations MUST support the
          internationalization extensions of RFC 6532.  Support
          for the obsolete obs-local-part, obs-domain, and
          obs-qtext in RFC 5322 is not required.

          The domain part may use both A-labels and U-labels
          (see RFC 5890).  The canonical format of the domain part
          uses lowercase characters and U-labels (RFC 5890) where
          applicable.";
       reference
         "RFC 5322: Internet Message Format
          RFC 5890: Internationalized Domain Names in Applications
                    (IDNA): Definitions and Document Framework
          RFC 6532: Internationalized Email Headers";
     }
   }
   <CODE ENDS>

5.  IANA Considerations

   This document reuses the URIs for "ietf-yang-types" and "ietf-inet-
   types" in the "IETF XML Registry" [RFC3688].

   Per this document, IANA has updated the "YANG Module Names" registry
   to reference this RFC instead of [RFC6991] for the "ietf-yang-types"
   and "ietf-inet-types" modules.  Following the format in [RFC6020],
   these registrations have been made.

   Name:  ietf-yang-types
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-yang-types
   Prefix:  yang
   Reference:  RFC 9911

   Name:  ietf-inet-types
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-inet-types
   Prefix:  inet
   Reference:  RFC 9911

6.  Security Considerations

   This document defines common data types using the YANG data modeling
   language.  The definitions themselves have no security impact on the
   Internet, but the usage of these definitions in concrete YANG modules
   might have.  The security considerations spelled out in the YANG
   specification [RFC7950] apply for this document as well.

7.  References

7.1.  Normative References

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

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/info/rfc3339>.

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

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC4007]  Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and
              B. Zill, "IPv6 Scoped Address Architecture", RFC 4007,
              DOI 10.17487/RFC4007, March 2005,
              <https://www.rfc-editor.org/info/rfc4007>.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, DOI 10.17487/RFC4291, February
              2006, <https://www.rfc-editor.org/info/rfc4291>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

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

   [RFC9499]  Hoffman, P. and K. Fujiwara, "DNS Terminology", BCP 219,
              RFC 9499, DOI 10.17487/RFC9499, March 2024,
              <https://www.rfc-editor.org/info/rfc9499>.

   [RFC9557]  Sharma, U. and C. Bormann, "Date and Time on the Internet:
              Timestamps with Additional Information", RFC 9557,
              DOI 10.17487/RFC9557, April 2024,
              <https://www.rfc-editor.org/info/rfc9557>.

   [RFC9562]  Davis, K., Peabody, B., and P. Leach, "Universally Unique
              IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May
              2024, <https://www.rfc-editor.org/info/rfc9562>.

   [XPATH]    Clark, J., Ed. and S. DeRose, Ed., "XML Path Language
              (XPath) Version 1.0", W3C Recommendation, 16 November
              1999, <http://www.w3.org/TR/xpath-10>.

   [XSD-TYPES]
              Peterson, D., Ed., Gao, S., Ed., Malhotra, A., Ed.,
              Sperberg-McQueen, C., Ed., and H. S. Thompson, Ed., "W3C
              XML Schema Definition Language (XSD) 1.1 Part 2:
              Datatypes", W3C Recommendation, 5 April 2012,
              <https://www.w3.org/TR/xmlschema11-2/>.

7.2.  Informative References

   [RFC0768]  Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              DOI 10.17487/RFC0768, August 1980,
              <https://www.rfc-editor.org/info/rfc768>.

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <https://www.rfc-editor.org/info/rfc791>.

   [RFC0952]  Harrenstien, K., Stahl, M., and E. Feinler, "DoD Internet
              host table specification", RFC 952, DOI 10.17487/RFC0952,
              October 1985, <https://www.rfc-editor.org/info/rfc952>.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

   [RFC1123]  Braden, R., Ed., "Requirements for Internet Hosts -
              Application and Support", STD 3, RFC 1123,
              DOI 10.17487/RFC1123, October 1989,
              <https://www.rfc-editor.org/info/rfc1123>.

   [RFC1930]  Hawkinson, J. and T. Bates, "Guidelines for creation,
              selection, and registration of an Autonomous System (AS)",
              BCP 6, RFC 1930, DOI 10.17487/RFC1930, March 1996,
              <https://www.rfc-editor.org/info/rfc1930>.

   [RFC2317]  Eidnes, H., de Groot, G., and P. Vixie, "Classless IN-
              ADDR.ARPA delegation", BCP 20, RFC 2317,
              DOI 10.17487/RFC2317, March 1998,
              <https://www.rfc-editor.org/info/rfc2317>.

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <https://www.rfc-editor.org/info/rfc2474>.

   [RFC2578]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Structure of Management Information
              Version 2 (SMIv2)", STD 58, RFC 2578,
              DOI 10.17487/RFC2578, April 1999,
              <https://www.rfc-editor.org/info/rfc2578>.

   [RFC2579]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Textual Conventions for SMIv2",
              STD 58, RFC 2579, DOI 10.17487/RFC2579, April 1999,
              <https://www.rfc-editor.org/info/rfc2579>.

   [RFC2780]  Bradner, S. and V. Paxson, "IANA Allocation Guidelines For
              Values In the Internet Protocol and Related Headers",
              BCP 37, RFC 2780, DOI 10.17487/RFC2780, March 2000,
              <https://www.rfc-editor.org/info/rfc2780>.

   [RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              DOI 10.17487/RFC2782, February 2000,
              <https://www.rfc-editor.org/info/rfc2782>.

   [RFC2856]  Bierman, A., McCloghrie, K., and R. Presuhn, "Textual
              Conventions for Additional High Capacity Data Types",
              RFC 2856, DOI 10.17487/RFC2856, June 2000,
              <https://www.rfc-editor.org/info/rfc2856>.

   [RFC3289]  Baker, F., Chan, K., and A. Smith, "Management Information
              Base for the Differentiated Services Architecture",
              RFC 3289, DOI 10.17487/RFC3289, May 2002,
              <https://www.rfc-editor.org/info/rfc3289>.

   [RFC3305]  Mealling, M., Ed. and R. Denenberg, Ed., "Report from the
              Joint W3C/IETF URI Planning Interest Group: Uniform
              Resource Identifiers (URIs), URLs, and Uniform Resource
              Names (URNs): Clarifications and Recommendations",
              RFC 3305, DOI 10.17487/RFC3305, August 2002,
              <https://www.rfc-editor.org/info/rfc3305>.

   [RFC3595]  Wijnen, B., "Textual Conventions for IPv6 Flow Label",
              RFC 3595, DOI 10.17487/RFC3595, September 2003,
              <https://www.rfc-editor.org/info/rfc3595>.

   [RFC3927]  Cheshire, S., Aboba, B., and E. Guttman, "Dynamic
              Configuration of IPv4 Link-Local Addresses", RFC 3927,
              DOI 10.17487/RFC3927, May 2005,
              <https://www.rfc-editor.org/info/rfc3927>.

   [RFC4001]  Daniele, M., Haberman, B., Routhier, S., and J.
              Schoenwaelder, "Textual Conventions for Internet Network
              Addresses", RFC 4001, DOI 10.17487/RFC4001, February 2005,
              <https://www.rfc-editor.org/info/rfc4001>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4340]  Kohler, E., Handley, M., and S. Floyd, "Datagram
              Congestion Control Protocol (DCCP)", RFC 4340,
              DOI 10.17487/RFC4340, March 2006,
              <https://www.rfc-editor.org/info/rfc4340>.

   [RFC4502]  Waldbusser, S., "Remote Network Monitoring Management
              Information Base Version 2", RFC 4502,
              DOI 10.17487/RFC4502, May 2006,
              <https://www.rfc-editor.org/info/rfc4502>.

   [RFC4592]  Lewis, E., "The Role of Wildcards in the Domain Name
              System", RFC 4592, DOI 10.17487/RFC4592, July 2006,
              <https://www.rfc-editor.org/info/rfc4592>.

   [RFC5017]  McWalter, D., Ed., "MIB Textual Conventions for Uniform
              Resource Identifiers (URIs)", RFC 5017,
              DOI 10.17487/RFC5017, September 2007,
              <https://www.rfc-editor.org/info/rfc5017>.

   [RFC5131]  McWalter, D., Ed., "A MIB Textual Convention for Language
              Tags", RFC 5131, DOI 10.17487/RFC5131, December 2007,
              <https://www.rfc-editor.org/info/rfc5131>.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              DOI 10.17487/RFC5322, October 2008,
              <https://www.rfc-editor.org/info/rfc5322>.

   [RFC5646]  Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
              Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
              September 2009, <https://www.rfc-editor.org/info/rfc5646>.

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

   [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
              Address Text Representation", RFC 5952,
              DOI 10.17487/RFC5952, August 2010,
              <https://www.rfc-editor.org/info/rfc5952>.

   [RFC6021]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6021, DOI 10.17487/RFC6021, October 2010,
              <https://www.rfc-editor.org/info/rfc6021>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6532]  Yang, A., Steele, S., and N. Freed, "Internationalized
              Email Headers", RFC 6532, DOI 10.17487/RFC6532, February
              2012, <https://www.rfc-editor.org/info/rfc6532>.

   [RFC6793]  Vohra, Q. and E. Chen, "BGP Support for Four-Octet
              Autonomous System (AS) Number Space", RFC 6793,
              DOI 10.17487/RFC6793, December 2012,
              <https://www.rfc-editor.org/info/rfc6793>.

   [RFC6991]  Schoenwaelder, J., Ed., "Common YANG Data Types",
              RFC 6991, DOI 10.17487/RFC6991, July 2013,
              <https://www.rfc-editor.org/info/rfc6991>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

   [RFC9260]  Stewart, R., Tüxen, M., and K. Nielsen, "Stream Control
              Transmission Protocol", RFC 9260, DOI 10.17487/RFC9260,
              June 2022, <https://www.rfc-editor.org/info/rfc9260>.

   [RFC9293]  Eddy, W., Ed., "Transmission Control Protocol (TCP)",
              STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022,
              <https://www.rfc-editor.org/info/rfc9293>.

   [ISO-8601] ISO/IEC, "Data elements and interchange formats --
              Information interchange -- Representation of dates and
              times", ISO/IEC 8601:2000, December 2008,
              <https://www.iso.org/standard/26780.html>.

   [ISO-9834-1]
              ISO/IEC, "Information technology -- Procedures for the
              operation of object identifier registration authorities --
              Part 1: General procedures and top arcs of the
              international object identifier tree", ISO/
              IEC 9834-1:2012, 2012,
              <https://www.iso.org/standard/58055.html>.

   [IEEE-802-2024]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Networks: Overview and Architecture", IEEE Std 802-2024,
              DOI 10.1109/IEEESTD.2025.10935844, March 2025,
              <https://doi.org/10.1109/IEEESTD.2025.10935844>.

   [Err4076]  RFC Errata, Erratum ID 4076, RFC 6991,
              <https://www.rfc-editor.org/errata/eid4076>.

   [Err5105]  RFC Errata, Erratum ID 5105, RFC 6991,
              <https://www.rfc-editor.org/errata/eid5105>.

Acknowledgments

   The following people contributed significantly to the original
   version of this document, which was published as [RFC6021]: Andy
   Bierman, Martin Björklund, Balazs Lengyel, David Partain, and Phil
   Shafer.

   Helpful comments on various draft versions of this document were
   provided by the following individuals: Andy Bierman, Martin
   Björklund, Benoît Claise, Joel M. Halpern, Ladislav Lhotka, Lars-
   Johan Liman, and Dan Romascanu.

Author's Address

   Jürgen Schönwälder (editor)
   Constructor University
   Email: jschoenwaelder@constructor.university
