module ietf-yang-types {

     namespace "urn:ietf:params:xml:ns:yang:ietf-yang-types";
     prefix "yang";

     organization
      "IETF NETMOD (NETCONF Data Modeling Language) Working Group";

     contact
      "WG Web:   <http://tools.ietf.org/wg/netmod/>
       WG List:  <mailto:netmod@ietf.org>

       WG Chair: David Kessens
                 <mailto:david.kessens@nsn.com>

       WG Chair: Juergen Schoenwaelder
                 <mailto:j.schoenwaelder@jacobs-university.de>

       Editor:   Juergen Schoenwaelder
                 <mailto:j.schoenwaelder@jacobs-university.de>";

     description
      "This module contains a collection of generally useful derived
       YANG data types.

       Copyright (c) 2013 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 Simplified BSD License
       set forth in Section 4.c of the IETF Trust's Legal Provisions
       Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC 6991; see
       the RFC itself for full legal notices.";

     revision 2013-07-15 {
       description
        "This revision adds the following new data types:
         - yang-identifier
         - hex-string
         - uuid
         - 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 such
         other times can occur, for example, the creation of
         a schema node of type counter32 at times other than
         re-initialization, 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 yang:counter32;
       default "0";
       description
        "The zero-based-counter32 type represents a counter32
         that has the defined 'initial' value zero.

         A schema node of 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 schema node
         of 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 such
         other times can occur, for example, the creation of
         a schema node of type counter64 at times other than
         re-initialization, 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 yang:counter64;
       default "0";
       description
        "The zero-based-counter64 type represents a counter64 that
         has the defined 'initial' value zero.
         A schema node of 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 schema node
         of 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 (increases above) the maximum (minimum) value, the
         gauge32 also decreases (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]\d*))))'
               + '(\.(0|([1-9]\d*)))*';
       }
       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
        "ISO9834-1: Information technology -- Open Systems
         Interconnection -- Procedures for the operation of OSI
         Registration Authorities: General procedures and top
         arcs of the ASN.1 Object Identifier tree";
     }

     typedef object-identifier-128 {
       type object-identifier {
         pattern '\d*(\.\d*){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)";
     }

     typedef yang-identifier {
       type string {
         length "1..max";
         pattern '[a-zA-Z_][a-zA-Z0-9\-_.]*';
         pattern '.|..|[^xX].*|.[^mM].*|..[^lL].*';
       }
       description
         "A YANG identifier string as defined by the 'identifier'
          rule in Section 12 of RFC 6020.  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.

          A YANG identifier MUST NOT start with any possible
          combination of the lowercase or uppercase character
          sequence 'xml'.";
       reference
         "RFC 6020: YANG - A Data Modeling Language for the Network
                    Configuration Protocol (NETCONF)";
     }

     /*** collection of types related to date and time***/

     typedef date-and-time {
       type string {
         pattern '\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?'
               + '(Z|[\+\-]\d{2}:\d{2})';
       }
       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.

         The date-and-time type is compatible with the dateTime XML
         schema type with the following notable exceptions:

         (a) The date-and-time type does not allow negative years.

         (b) The date-and-time time-offset -00:00 indicates an unknown
             time zone (see RFC 3339) while -00:00 and +00:00 and Z
             all represent the same time zone in dateTime.

         (c) The canonical format (see below) of data-and-time values
             differs from the canonical format used by the dateTime XML
             schema type, which requires all times to be in UTC using
             the time-offset 'Z'.

         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
         in case a server follows automatically daylight saving time
         (DST) time zone offset changes.  The canonical format for
         date-and-time values with an unknown time zone (usually
         referring to the notion of local time) uses the time-offset
         -00:00.";
       reference
        "RFC 3339: Date and Time on the Internet: Timestamps
         RFC 2579: Textual Conventions for SMIv2
         XSD-TYPES: XML Schema Part 2: Datatypes Second Edition";
     }

     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 yang:timeticks;
       description
        "The timestamp type represents the value of an associated
         timeticks schema node 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 attribute 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
         attribute 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 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 an IEEE 802 MAC address.
         The canonical representation uses lowercase characters.

         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 4122.  The canonical representation uses
         lowercase characters.

         The following is an example of a UUID in string representation:
         f81d4fae-7dec-11d0-a765-00a0c91e6bf6
         ";
       reference
        "RFC 4122: A Universally Unique IDentifier (UUID) URN
                   Namespace";
     }

     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.";
     }
   }