I realized as I got further into the design that there were some unstated things about what I'm proposing. So here is a complete statement, AFAIK: Using /a will have the following effects: 1) \s, \d, \w will match only the appropriate ASCII characters 2) [:posix:] will match only (the appropriate) ASCII characters 3) /i of ASCII characters will match only ASCII characters. eg. the Kelvin sign will not match 'k' 4) /i of non-ASCII characters will obey Unicode semantics, eg, a capital and lower case Greek beta will match, as will the Angstrom sign and an A with a circle above. 5) \p{} will match in the full Unicode range, so that \p{Nd} will match many more characters than the 10 matched by \d. 6) All of the above is true as well on EBCDIC platforms whose native character set is Latin1. ie. under /a they would behave identically as an ASCII platform would.Thread Next