VMS Help Lexicals, F$TRNLNM, Return Value  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The equivalence name or attribute of the specified logical
    name. The return value can be a character string or an integer,
    depending on the arguments you specify with the F$TRNLNM
    function. If no match is found, a null string ("")  is returned.