I'm really hazy going back this far, but wasn't it that it worked in Firefox and Opera, but then IE could be handled using magic HTML comments that served it sp

I'm really hazy going back this far, but wasn't it that it worked in Firefox and Opera, but then IE could be handled using magic HTML comments that served it special separate rules? I know sometimes IE's vendor-specific CSS "expressions" system could be used to compute properties like max-width and so-on that it didn't otherwise support, and it was nice to be able to do that without requiring a JS polyfill.