Seems like a riff on the famous Perl Compatible Regular Expressions library (http://www.pcre.org), which is used in a bunch of high-profile things (PHP, and Apache Server, for starters). Kind of like "less" vs "more".
So a bit of an inside joke I guess, but most people familiar with regexes will probably have heard of PCRE, so it's not a terribly obscure reference. I liked it :)
PCRE is a set of extensions to RE to enable parsing of nonregular grammars. This is just RE. It's like calling some hypothetical language C++--. It doesn't make sense.
Well, if I designed a language that was C++ but stripped of some specific features for a purpose that made it less than C++, but still not quite just C, I might call it C++-- as a joke. In that respect, I think it makes perfect sense.
So a bit of an inside joke I guess, but most people familiar with regexes will probably have heard of PCRE, so it's not a terribly obscure reference. I liked it :)