VMS Help DSR, DSR Commands, .TAB STOPS, Defaults  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    o  If you enter the .TAB STOPS command without number or comma
       specifications, the use of all tab stops is suspended and the
       tab character is equivalent to a space.

    o  If you do not enter the .TAB STOPS command, successive tab
       characters work as if you had set a tab stop every eight
       positions; that is, as if you had entered .TAB STOPS 8,16,24,
       and so on. Note that because .PAGE SIZE has a width limit of
       150, 149 is the practical limit for .TAB STOPS.