Syntax
=====

.. code-block:: text

    interspectrum = REST_SPEC_PHYS (
        ◆ | BASE_ELAS_FLUI = melasflu,
          | MODE_MECA = mode_meca,
        # If: exists (" BASE_ELAS_FLUI ")
            ◆ VITE_FLUI = float,
            ◇ PRECISION = float (default: 0.001),
        ◇ BANDE = float,
        ◇ NUME_ORDRE = int,
        ◇ TOUT_ORDRE =/"OUI ",
                       /"NON" (by default),
        ◆ INTE_SPEC_GENE = interspectrum,
        ◆/GROUP_NO = grno,
        ◇ GROUP_MA = Grma,
        ◆ NOM_CMP = text,
        ◆ NOM_CHAM =/"DEPL ",
                     /"VITE ",
                     /"ACCE ",
                     /"EFGE_ELNO ",
                     /"SIPO_ELNO ",
                     /"SIGM_ELNO ",
                     /"FORC_NODA ",
        ◇ MODE_STAT = meca fashion,
        ◇ EXCIT = _F (
             ◆ | GROUP_NO = group,
             ◆ NOM_CMP = text,
          ),
        ◇ MOUVEMENT =/"RELATIF ",
                      /"ABSOLU" (by default),
                      /"DIFFERENTIEL ",
        ◇ OPTION =/"DIAG_TOUT ",
                   /"DIAG_DIAG" (by default),
                   /"TOUT_TOUT ",
                   /"TOUT_DIAG ",
        ◇ TITRE = text,
    )
    
    ◆: mandatory
    ◇: optional
    : present by default
    &: together
    /: only one among
    |: several possible choices