VMS Help DSR, DSR Flags, Space  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The Space flag (#) produces one unexpandable space (not affected
    by justification) in the output file for every flag character
    inserted in the input file. If you insert the flag between two
    words, DSR treats them as one word (although they will appear
    as separate words in the output file). Therefore, you should not
    type any spaces before or after typing the Space flag.

    The flag can directly follow an Underline flag (&#) to cause the
    underlining of an unexpandable space.

1 - Default

    Recognition is turned on.