There are only a few flags in UnterMUD.  They are 'isdark', 'local', 
'isroom', 'isplayer', and 'wizard.'  Each of these is of type "flag".  The
flags 'isroom' and 'isplayer' are set automatically when a room or a player is
built.  They can only be unset (or set) by a wizard.  They just serve to help
identify what the object is.

    Note that there are no flags for "isexit" or "isobject".  It is possible
to distinguish these from rooms and players because there are two different
types of object IDs in UnterMUD, unqualified object ids and fully qualified
object ids which include the mud's name along with the object number.  For
example, 123@UnterStairCase is a fully qualified name.  Since only objects
with a fully qualified object id are allowed to move to another UnterMUD,
players and things have this sort of object id, and rooms and exits do not. 
A thing, therefore, looks just like a player, except it does not have the
player flag (and it stays in the contents list of a room, not in the player
list).  Exits are identified similarly.

    The 'wizard' flag is settable only by a wizard, or by using the _wizard
command.  In order to use the _wizard command to set your wizard flag, you
must be in the list of wizards on the system object, and know the wizard
password.

    The 'isdark' flag works almost the same as in TinyMUD.  When a room is
set dark, a 'look' will show none of the room contents, even if you own
something in the room.  Players set dark are similar in behaviour to rooms,
essentially hiding their contents.  Only a wizard can set a player dark.  An
object set dark is not listed in the contents when you look at the room or
player containing it.  If you are the owner of a room or player, you may see
all the contents of it by doing an 'examine', a player can also always see
their own contents using "inventory".

    The 'local' flag is only meaningful for players and objects.  When set,
the player or object (or player holding the object) is not allowed to move
through a cyberportal to another Unter.  This is especially useful for
players without nice clients (like raw telnet), and for people who want to
make sure their objects don't get lost on another mud.

    Unlike in TinyMUD 'linkok' is actually a boolean, much like lock.  This
means that you can set your room linkok only for a certain player, or only
for people holding a certain item, and so forth.  In a boolean, the letters
"T" and "F" mean 'true' or 'false', respectively.  This allows you to set a
room linkok to everyone with just "set here linkok=T" and get TinyMUD style
behaviour.  Just think of 'linkok' as a fancy lock.