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

       /ECHO (default)
       /NOECHO

    Controls whether the command line is displayed after the key has
    been pressed. Do not use /NOECHO with /NOTERMINATE.