Here you go:
Yorkshire Terrier Club of America (Awards) This is from the Yorkshire Terrier Club of America. They are the ones that write the breed standard and send it along to the AKC. They make it very clear that there are no "teacups."
Myself, I don't get all shook up about the term being used. Other breeds use the term to describe the smaller members of their breed. Unfortunately some unscrupulous breeders made the term undesireable as they kept breeding even the littlest of the Yorkies to capitalize on the "teacup" idea. If not for that, I would not see anythign wrong with it. But, the YTCA says no to teacups, so that is the last word as far as AKC standards goes.
He may have some paperwork saying teacup, but it probably something typed up by the breeder, not a registery.
Oops ... I was a minute too late with all that slow typing of mine.... lol!