Hmmm.. I think it only does some of the markup, only those things which only happen if they are on one one line.
(for instance, ==== This isn't a heading ====)
No, it's the other way around; it handles the markup for stuff like lists, that span multiple lines.
specifically, it does the stuff in WikiLinesToHtml plus the stuff in CommonMarkup under the "if ($doLines)" (near the bottom).
It is called only by WikiToHTML.
CategoryWikiMarkupFunction?
CategoryFunction?