I am not an expert on the yorkie standard, but i think that the YTCA would be the best place to go in order to get information on that standard.
As for other threads that you might read here, even though someone may speak out on something they like, it doesn't mean that these specific breeding practices create a good dog. The YTCA has its standing in the yorkie community for a reason and i would go by their standards.
I hope you find the perfect doggie for you and one that will make you happy
Good luck!!!