/sys$common/syshlp/helplib.hlb SPAWN, Qualifiers, /PROMPT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /PROMPT[=string]

    Specifies the prompt string for DCL to use in the subprocess. The
    default is the prompt of the parent process.

    The string can consist of more than one character. All valid
    ASCII characters can be used in the string. The string must be
    enclosed in quotation marks (" ")  if it contains spaces, special
    characters, or lowercase characters. Otherwise, letters are
    automatically converted to uppercase, and leading and trailing
    spaces are removed.

    If no string is specified, the dollar sign ($)  DCL default
    prompt string is used for the subprocess.