The commas instead of dots confuse me. I'd argue that ie7,replace,ie6 is a combination that isn't really necessary... what purpose would it (practically) solve?
Re: Rewriting the skin file parser...
« Reply #45, on May 27th, 2012, 03:41 PM »
* Sort selector lists before generating the CSS files. This helps a bit with overall gzip compression rates. (Class-CSS.php)