Library /sys$common/syshlp/nclhelp.hlb set, device, dump_destination  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    File specification to hold the contents of the device's microcode
    when a dump occurs.

    For Tru64 UNIX, the default value for the dump destination is
    /usr/var/xxx.dump where xxx is the device specification. For
    example: /usr/var /dsv.dump.