Syntax
=====

.. code-block:: text

    interspectrum = CALC_SPEC (
        ◆/TAB_ECHANT = _F (
               ◆ NOM_TAB = table,
               ◇ LONGUEUR_DUREE = float,
               ◇ LONGUEUR_POURCENT = float,
               ◇ LONGUEUR_NB_PTS = int,
               ◇ RECOUVREMENT_DUREE = float,
               ◇ RECOUVREMENT_POURCENT = float,
               ◇ RECOUVREMENT_NB_PTS = int,
            ),
          /ECHANT = _F (
               ◆ NUME_ORDRE_I = int,
               ◆ NUME_MES = int,
               ◆ FONCTION = function,
            ),
        ◆/INTERSPE = _F (
               ◇ FENETRE =/"RECT" (by default),
                           /"HAMM ",
                           /"HANN ",
                           /"EXPO ",
                           /"PART ",
               # If: FENETRE == 'EXPO' or FENETRE == 'PART'
                   ◇ DEFI_FENE = float,
            ),
          /TRANSFERT = _F (
               ◇ ESTIM =/"H1" (by default),
                         /"H2",
                         /"CO",
               ◆ REFER = int,
               ◇ FENETRE =/"RECT" (by default),
                           /"HAMM ",
                           /"HANN ",
                           /"EXPO ",
                           /"PART ",
               # If: FENETRE == 'EXPO' or FENETRE == 'PART'
                   ◇ DEFI_FENE = float,
            ),
        ◇ TITRE = text,
        ◇ INFO =/1 (by default),
                 /2,
    )
    
    ◆: mandatory
    ◇: optional
    : present by default
    &: together
    /: only one among
    |: several possible choices