The ATTRIBUTES directive option ALLOW_NULL enables a corresponding dummy argument to pass a NULL pointer (defined by a zero or the NULL intrinsic) by value for the argument. It takes the following form:
cDEC$ ATTRIBUTES ALLOW_NULL :: arg
c |
Is one of the following: C (or c), !, or *. (See Syntax Rules for Compiler Directives.) |
arg |
Is the name of the argument. |
ALLOW_NULL is only valid if the REFERENCE option is also specified; otherwise, it has no effect.