Hi, Nora.
 
The AW that you see on messages from Europe, especially the
German-speaking countries, is a contraction of "Antwort" which
means "Answer." (Guten tag, Helmut und Alle!) Their "Antwort" to
our "Re:" for "Regarding" or "Reply" or "Replying to" or...
Well, you get picture.
 
Aloha,
 
makuabob (a.k.a. Bob Dayle)
 
Oh! I've just added an index of the maps used in the thirty years
of Hawaiian Shell News. You'll find that handy if you want to
know where you might be going on a trip -- and the article is
right there with it!
                        http://www.geocities.com/~makuabob/