Quote Originally Posted by phil h
I just clicked on the link in this post, the Lord Lyon him self had a flag on his jacket, wasn't that what heraldry was invented for?
for wearing on a tunic over armour to identify a knight?
There are several types of armoral bearing types. That used for a shield can be displayed as a shield, surcoat, flag or in many other ways.

There are others used SPECIFICALLY for a flag, which has different "rules" than a shield-type device. The US has many more rules than most (passed by the US Congress). There actually is a shield version that can be used ore as typical heraldry and uses the stars on blue and 13 stripes, but in a different formation (vertical) than the flag itself.

A common application long "tag" that is a series of white stars on blue and 3 (red-white-red) or 5 (red-white-red-white-red) stripes. This one implies the flag, but is not a direct application.

Many nations use flags based upon medieval shield designs, so the "appropriate" applications are much more wide open. The Lord Lyon knows, dictates, and applies the appropriate rules as necessary.