[Chixla] Anyone know anything about children's sizes?

[SMichelle]

A lot of people purchased the smallest women's sizes of t-shirts with
the last batch for their children (Small 0-4 Ladies and Medium 4-6
Ladies).  I'd like to also make some accomodations for children's sizes,
but I am clueless as to a kids size chart. 
The sizes available are:
Youth-Small (6-8 Children)               
Youth-Medium (10-12 Children) 
Youth-Large (14-16 Children) 
Anyone know what these mean, or some have some kind of age/size
comparison? 
Thanks!
Sharon Michelle