module openconfig-extensions {

    yang-version 1;

    namespace
      "http://openconfig.net/yang/openconfig-ext";

    prefix oc-ext;

    organization "OpenConfig working group";

    contact
      "OpenConfig working group
www.openconfig.net";

    description
      "This module provides extensions to the YANG language to allow
OpenConfig specific functionality and meta-data to be defined.";

    revision "2020-06-16" {
      description
        "Add extension for POSIX pattern statements.";
      reference
        "0.5.0";

    }

    revision "2018-10-17" {
      description
        "Add extension for regular expression type.";
      reference
        "0.4.0";

    }

    revision "2017-04-11" {
      description
        "rename password type to 'hashed' and clarify description";
      reference
        "0.3.0";

    }

    revision "2017-01-29" {
      description
        "Added extension for annotating encrypted values.";
      reference
        "0.2.0";

    }

    revision "2015-10-09" {
      description
        "Initial OpenConfig public release";
      reference
        "0.1.0";

    }


    extension openconfig-version {
      argument "semver" {
        yin-element false;
      }
      description
        "The OpenConfig version number for the module. This is
expressed as a semantic version number of the form:
 x.y.z
where:
 * x corresponds to the major version,
 * y corresponds to a minor version,
 * z corresponds to a patch version.
This version corresponds to the model file within which it is
defined, and does not cover the whole set of OpenConfig models.

Individual YANG modules are versioned independently -- the
semantic version is generally incremented only when there is a
change in the corresponding file.  Submodules should always
have the same semantic version as their parent modules.

A major version number of 0 indicates that this model is still
in development (whether within OpenConfig or with industry
partners), and is potentially subject to change.

Following a release of major version 1, all modules will
increment major revision number where backwards incompatible
changes to the model are made.

The minor version is changed when features are added to the
model that do not impact current clients use of the model.

The patch-level version is incremented when non-feature changes
(such as bugfixes or clarifications to human-readable
descriptions that do not impact model functionality) are made
that maintain backwards compatibility.

The version number is stored in the module meta-data.";
    }

    extension openconfig-hashed-value {
      description
        "This extension provides an annotation on schema nodes to
indicate that the corresponding value should be stored and
reported in hashed form.

Hash algorithms are by definition not reversible. Clients
reading the configuration or applied configuration for the node
should expect to receive only the hashed value. Values written
in cleartext will be hashed. This annotation may be used on
nodes such as secure passwords in which the device never reports
a cleartext value, even if the input is provided as cleartext.";
    }

    extension regexp-posix {
      description
        "This extension indicates that the regular expressions included
within the YANG module specified are conformant with the POSIX
regular expression format rather than the W3C standard that is
specified by RFC6020 and RFC7950.";
    }

    extension posix-pattern {
      argument "pattern" {
        yin-element false;
      }
      description
        "Provides a POSIX ERE regular expression pattern statement as an
alternative to YANG regular expresssions based on XML Schema Datatypes.
It is used the same way as the standard YANG pattern statement defined in
RFC6020 and RFC7950, but takes an argument that is a POSIX ERE regular
expression string.";
      reference
        "POSIX Extended Regular Expressions (ERE) Specification:
        https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04";

    }

    extension telemetry-on-change {
      description
        "The telemetry-on-change annotation is specified in the context
of a particular subtree (container, or list) or leaf within the
YANG schema. Where specified, it indicates that the value stored
by the nodes within the context change their value only in response
to an event occurring. The event may be local to the target, for
example - a configuration change, or external - such as the failure
of a link.

When a telemetry subscription allows the target to determine whether
to export the value of a leaf in a periodic or event-based fashion
(e.g., TARGET_DEFINED mode in gNMI), leaves marked as
telemetry-on-change should only be exported when they change,
i.e., event-based.";
    }

    extension telemetry-atomic {
      description
        "The telemetry-atomic annotation is specified in the context of
a subtree (containre, or list), and indicates that all nodes
within the subtree are always updated together within the data
model. For example, all elements under the subtree may be updated
as a result of a new alarm being raised, or the arrival of a new
protocol message.

Transport protocols may use the atomic specification to determine
optimisations for sending or storing the corresponding data.";
    }

    extension operational {
      description
        "The operational annotation is specified in the context of a
grouping, leaf, or leaf-list within a YANG module. It indicates
that the nodes within the context are derived state on the device.

OpenConfig data models divide nodes into the following three categories:

- intended configuration - these are leaves within a container named
  'config', and are the writable configuration of a target.
- applied configuration - these are leaves within a container named
  'state' and are the currently running value of the intended configuration.
- derived state - these are the values within the 'state' container which
  are not part of the applied configuration of the device. Typically, they
  represent state values reflecting underlying operational counters, or
  protocol statuses.";
    }

    extension catalog-organization {
      argument "org" {
        yin-element false;
      }
      description
        "This extension specifies the organization name that should be used within
the module catalogue on the device for the specified YANG module. It stores
a pithy string where the YANG organization statement may contain more
details.";
    }

    extension origin {
      argument "origin" {
        yin-element false;
      }
      description
        "This extension specifies the name of the origin that the YANG module
falls within. This allows multiple overlapping schema trees to be used
on a single network element without requiring module based prefixing
of paths.";
    }
  }  // module openconfig-extensions