I was (mistakenly) under the impression that a character class that ended with a dash was a syntax error, because perl treated it as though it were an unfinished range.

After reading your post, I tried it in Perl, and of course it works fine. So, I thought it must be an AWKism, but no, it works there too.

In short, I have no idea why I thought you couldn't end a character class with a dash. Lets just say it must be an age thing.

Thanks for the enlightenment.