You may use on error here, similar to:

ON ERROR llerror=.t.
llerror=.f.
DO hi.exe
on error
if llerror
*Not exist?
endif


>Is there a way to detect the existance of a procedure or function at runtime prior to calling it?
>
>The reason, is that we have some procedure calls as dynamic table links. Need to make sure the procedure/function is accessible to the calling module prior to invoking it to prevent fatal run-time errors.