It's U10 here (as in under 10 - 2003 & 2004 birthyears as opposed to 10U 2002 & 2003 birthyears) as mandated by our governing body. However, where you are, no idea. Personally, i'm just happy to see so much discussion about the U which so doesnt get it's due in American English.
Up here, we use it more often. Colour, Honour, Cheque, Labour, Behaviour and Humour... (for example)
And it's Z ("zed") not Z ("zee") - don't beleive me? Men in Black got it right. LOL sorry, i coudlnt resist