The FDL$RELEASE routine deallocates the virtual memory used by
    the OpenVMS RMS control blocks created by FDL$PARSE. You must
    use FDL$PARSE to populate the control blocks if you plan to
    deallocate memory later with FDL$RELEASE.

    Format

      FDL$RELEASE  [fab_pointer] [,rab_pointer] [,flags]

                   [,badblk_addr]