I see both "US-ASCII" and "ASCII" are used in: http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-54
If they mean the same thing, one should be used consistently. In the document, US-ASCII seems to mean encoding while ASCII mean charset. Is this common? (I guess US-ASCII is commonly considered as an alias for ASCII. http://en.wikipedia.org/wiki/ASCII#Aliases ) Yuzo