Syntax
=====

.. code-block:: text

    evol_char = LIRE_PLEXUS (
        ◇ UNITE = unit (default: 19),
        ◇ FORMAT = "IDEAS ",
        ◆ MAIL_PLEXUS = mesh,
        ◆ MAILLAGE = mesh,
        ◆ MODELE = model,
        ◆/TOUT_ORDRE = "OUI" (or not specified),
          /NUME_ORDRE = int,
          /INST = float,
          /LIST_INST = listr8,
          /LIST_ORDRE = listis,
        # If: exists (" LIST_INST ") or exists (" INST ")
            ◇ CRITERE =/"RELATIF" (by default),
                        /"ABSOLU ",
            # If: (equal_to (" CRITERE ", 'RELATIF'))
                ◇ PRECISION = float (default: 1e-06),
            # If: (equal_to (" CRITERE ", 'ABSOLU'))
                ◆ PRECISION = float,
        ◇ TITRE = text,
    )
    
    ◆: mandatory
    ◇: optional
    : present by default
    &: together
    /: only one among
    |: several possible choices