Semantic question: short document heders, "to"

Hello everybody. 

I have a doubt that's more on the semantic realm that any applied urgency.

I am using docbook articles for any usual business document that is
not a big work, i.e. letters of intentions, short letters, etc.

All of these have in the title page a header with the usual:

 * To: name/company
 * From: name/company
 * Date: ...
 * Project: ...
 * Title: ...

For all this meta data I use articleinfo. But I can't find which
element (if any exists) is the right one for the "to" and "project"
part.

Any idea on this? 
Thanks to all for your attention. :-)

Regards...

-- 
Eduardo Mercovich
Buenos Aires - Argentina.