.. _user/services/structure/definitions:

***********
definitions
***********

*Definitions* are similar to parameters in that you can refer to them from
within the commissioning file. They are different to parameters as they are
intended for solely internal use, i.e. they can't be re-configured at any
time.

Values of definitions can be of any type - including object types - and be
referred to by the ``!ref`` or ``!merge`` function, similar to
:ref:`parameters <user/services/structure/parameters>`.

Example
=======

.. code-block:: yaml

  modbusEndpointDefaults:
    connectionId: !ref modbusConnection
    operation: subscribe
    interval: 1000
    address:
      fc: 3
      length: 2

In the above example using ``!ref modbusEndpointDefaults`` would result in
a the value:

.. code-block:: yaml

  connectionId: !ref modbusConnection
    operation: subscribe
    interval: 1000
    address:
      fc: 3
      length: 2