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)";
  }
}