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

    Makes the specified task the visible task, which is the task
    whose call stack and register set are the current context for
    looking up symbols, register values, routine calls, breakpoints,
    and so on. Commands such as EXAMINE are directed at the visible
    task. The /VISIBLE qualifier does not affect the active task.
    When using /VISIBLE, you must specify one task.