FLAG ON REFEREE UNIFORM

Question:
I met a USSF Grade 8 referee this weekend who was on a field next to the one was refereeing on. I noticed that he had a flag sewn to the sleeve of his uniform. Two part question:

Is this legal, and if so, how would we know (where in the documentation does this exist)?

This particular referee is English and the flag on his uniform was the Union Jack. Is this legal? Why/why not?

Thank you,

USSF answer (September 1, 2010):
If the referee chooses to wear it, the USA flag patch is to be worn on the left sleeve, between elbow and shoulder.

The wearing of the USA flag path was originally permitted as a reminder of 9/11 and is still allowed. There is no basis for a person registered with the U. S. Soccer Federation to be wearing the Union Jack on his uniform, no matter what his nationality.