No subject

sits up on the dias/whatever at court.

This is not the case in all kingdoms.  In some kingdoms, visiting royalty
sits with the populace unless specifically invited to join the crown up at
the front (usually this would be arranged ahead of time).  (This is the
view that it is a vacation for that royal and they can simply "hang out" at
a court for a change - unless they specifically wish to do otherwise.)

What this means: royalty visiting from other kingdoms may not be expecting
to sit at the front of a court.  It is a kindness to let them know about
this Ansteorran custom ahead of time.  Especially if they are getting on a
plane, they may not be planning to bring their
look-great-sitting-at-the-front-of-court garb.  Telling them about the
custom gives them the opportunity to pack a set of fancy garb, make sure
they have all the regalia, etc.

Telling the group hosting the court that a foreign royal will be present
will give them a chance to arrange for an additional throne/chair/whatever
since the royal may not be able to bring that depending upon how they are
traveling.  (Additional points are given for finding a throne cushion in
the right colors, etc. *grin*)

Mari