@SET (ME | (player)) = TELLALL
The TELLALL flag causes hidden objects to become visible, but only
to the players that have control over them.
Note: TELLALL does not make DARK exits visible, but it does cause
all conditionally-visible exits to appear on the [ Exits: ] line.
TELLALL is useful for builders who want to see everything in a
room that that may be visible at one time or another, or for
seeing their own dark/conditionally-visible groups on other players.
!TELLALL is useful for wizards who have no interest in seeing
other players dark/conditionally-visible groups, or the copious
conditionally-visible exits in the rooms they pass through.