This is a family of functions which test whether an Object is a member of the class called $<$CLASS$>$, or of any class derived from it.

RESULT = AST_ISA$<$CLASS$>$( THIS, STATUS )

THIS = INTEGER (Given)

STATUS = INTEGER (Given and Returned)

Object

AST_ISA$<$CLASS$>$ = LOGICAL

MEMBER = AST_ISAFRAME( OBJ, STATUS );

Tests whether Object OBJ is a member of the Frame class, or of any class derived from a Frame.

• Every AST class provides a function (AST_ISA$<$CLASS$>$) of this form, where $<$CLASS$>$ should be replaced by the class name.

• This function attempts to execute even if STATUS is set to an error value on entry, although no further error report will be made if it subsequently fails under these circumstances.

• A value of .FALSE. will be returned if this function should fail for any reason. In particular, it will fail if the pointer supplied does not identify an Object of any sort.