Blurb::
Name the variables block; helpful when there are multiple
Description::
The optional ``id_variables`` keyword accepts a string that uniquely
identifies this variables block.  A model can then use these variables
by specifying the same string in its ``variables_pointer``
specification.

*Default Behavior*

If the ``id_variables`` specification is omitted, a particular
variables specification will be used by a model only if that model
does not include an ``variables_pointer`` and the variables block was
the last (or only) one parsed.

*Usage Tips*

- It is a best practice to always use explicit variables IDs and  pointers to avoid confusion.


- If only one variables block exists, then ``id_variables`` can be  safely omitted from the variables block (and ``variables_pointer``  omitted from the model specification(s)), since there is no  ambiguity.
Topics::
block_identifier
Examples::
For example, a model specification including

.. code-block::

    model
      variables_pointer = 'V1'

will link to a response set with

.. code-block::

      id_variables = 'V1'


Theory::

Faq::

See_Also::
