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

    When a window definition is canceled, you can no longer use its
    name in a DISPLAY command. The CANCEL WINDOW command does not
    affect any displays.

    Related commands:

       (SHOW,CANCEL) DISPLAY
       (SET,SHOW) WATCH