VMS Help FDL Routines, FDL$RELEASE, Condition Values Returned  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    SS$_NORMAL         Normal successful completion.
    FDL$_INVBLK        Invalid RMS control block at virtual address
                       'hex-offset'.
    LIB$_BADBLOADR     Bad block address.
    RMS$_ACT           File activity precludes operation.
    RMS$_RNL           Record not locked.
    RMS$_RSA           Record stream currently active.
    SS$_ACCVIO         Access violation.