2. Syntax

char_acou = AFFE_CHAR_ACOU (
    ◆ MODELE = model,
    ◇ DOUBLE_LAGRANGE = "OUI ",
    ◆ | PRES_IMPO = _F (
           ◆ | ALL = "YES" (or not specified),
             | GROUP_MA = grma,
             | GROUP_NO = group,
           ◇ SANS_GROUP_MA = Grma,
           ◇ SANS_GROUP_NO = big,
           ◆ PRES = complex,
        ),
      | SPEED_FACE = _F (
           ◆ GROUP_MA = Grma,
           ◆/VNOR = complex,
        ),
      | UNIF_LINK = _F (
           ◆/GROUP_NO = grno,
             /GROUP_MA = grma,
           ◆ DDL = "PRES" (or not specified),
        ),
)

◆: mandatory
◇: optional
: present by default
&: together
/: only one among
|: several possible choices