Library /sys$common/syshlp/dbg$help.hlb DEBUG, ATTACH, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 process-name

    Specifies the process to which your terminal is to be attached.
    The process must already exist before you try to attach to it.
    If the process name contains nonalphanumeric or space characters,
    you must enclose it in quotation marks (").