Library /sys$common/syshlp/dbg$help.hlb DEBUG, Built in Symbols, %VISIBLE TASK  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    (Applies only to tasking programs.) Gives you the task that the
    debugger is using to do symbol lookups. This is the default task
    assumed by debugging commands when you do not (or cannot) specify
    a task. For example, the EXAMINE %R0 command displays register 0
    of the visible task.

    This is normally the same as %ACTIVE_TASK but can be changed
    using the SET TASK command.

    Example:

    DBG> SET TASK %TASK 2
    DBG> EVALUATE %VISIBLE
    %TASK 2