--On Thursday, December 18, 2014 16:05 -0800 Ned Freed <ned.freed@xxxxxxxxxxx> wrote: >> Actually, RFC 20 says, in its very first sentence, >> "...standard 7-bit ASCII embedded in an 8 bit byte whose high >> order bit is always 0". Unless I'm missing something, that >> is a mapping from a CCS (although ASCII defined those >> integers in Column/Row form rather than as single integers) >> and a CES. > > Yep, it's essentially a CES. The only thing missing is the > definition of the US-ASCII charset name. > >> So, possibly >> modulo references to different versions of ASCII (I don't have >> time to check whether the Charset definition for US-ASCII >> points to the same version of US-ASCII that RFC 20 does), RFC >> 20 and US-ASCII are more than just "essentially" the same". > > The CCSs appear identical to me. There may be some subtle > difference in how some control is defined in the ANSI > documents versus RFC 20, but that's getting pretty picky. If one pays attention only to the CCS and ignores character semantics (as you note, especially for C0 characters in columns 0 and 1), ASCII is unchanged from the time of its first publication, i.e., stable both before and after RFC 20. john