in reply to and (and friends) in sourcecode

"Non-ASCII" and "source code" sounds like you're just asking for trouble. Consider that not only does your code have to execute correctly, but it has to be documented, emailed, printed, and put into version control.

Have you considered using different notation (like hex) to pick up those values? If you did, you'd still have a correct regex and at the same time have ASCII source.

If it were me, I'd try *real* hard to make that happen.