Hi Rik and all,

Many words ending in -ize (American), have a preferred spelling -ise in
British English.

http://www.bartleby.com/68/45/5645.html

http://www.geocities.com/CapitolHill/Lobby/6524/spelling.html

On searching the Net, I also found an article claiming that
this was caused an influence from the French.

http://www.linguistlist.org/~ask-ling/archive-2000.1/msg00563.html

--Stewart (third generation American, but 1/4 English)

PS : The spell checker insists on writing synchronization (with Z, not S). It looks odd to me, any native English who can confirm this ? (or is it one of these subtile differences between British and American English)