Forgive me if this has been requested before.
I have been playing around with some text editors on OS X where the syntax definition files are defined using XML-like definition sheets. This seems much more structured and powerful than the *.syn files used in TextPad.
To defend TP somewhat, I have still not found anything as powerful and flexible on the Mac. BBEdit is good but it is a one-trick pony rather than a programming editor.
XML Syntax Definition Files
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