xxx is a trademark of yyy

[Alan Wexelblat]

The (U) has nothing to do with trademarks.  It simply means that the 
item in the box (note that it appears only on food items) is kosher with
either milk or meat.  (P) is used to indicate milk-only items, and (K) is
idicative of meat-only items.  These symbols usually indicate some form of
rabbinic supervision (ie the company ought not to go putting them on just
any item).