Syntax
=====

.. code-block:: text

    PRE_GMSH (
        ◇ UNITE_GMSH = unit (default: 19),
        ◇ UNITE_MAILLAGE = unit (default: 20),
    )
    
    ◆: mandatory
    ◇: optional
    : present by default
    &: together
    /: only one among
    |: several possible choices