Discussions of secure PHP coding. Security in software is important, so don't be afraid to ask. And when answering: be anal. Nitpick. No security vulnerability is too small.
I can't say that I've ever seen a page name like that, but what you posted as an example is just that: a name for an html page.
with the extension being .html, it probably is nothing more than just the name of the page (unless they are mapping .html to an isapi or cgi application). If they are mapping it, I suppose they could check the file name and do some processing on the server side according to the page name, but that would seem a pretty stupid way of doing things as they'd have to create separate names for each page anyway and they would already know which page it's on by virtue of the fact that it would have to be separate for each page.
if, like I mentioned above, they are mapping .html to some kind of server side application, I suppose it could be, but even then, it's not a "standard" format for mod_rewrite.