VMS Help RUNOFF, file, Qualifiers, /SEPARATE_UNDERLINE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SEPARATE_UNDERLINE[="character"]

    Positional qualifier.

    Prints underlines as separate characters on the next line instead
    of overstriking with underscores on the same line. The value
    specifies the character to be used for the underline character
    and defaults to a hyphen (-).  You can specify the underline
    character as a single printable character or as a number preceded
    by a radix indicator (%D, %O, or %X)  to represent the ASCII
    value of a printable or nonprintable character.

    This qualifier is incompatible with the /[NO]UNDERLINE_CHARACTER
    qualifier.