Head Profile

I was thinking of adding some different RELs to some of my links, and then using style-sheets (and maybe JS) to manipulate them, and I noticed that you can use the profile attribute on the head element if you use custom link types. But the HTML 4.01 spec doesn't seem to touch on how you should write the profile file. Can it just be a html file with a definition list of what the custom REL types are?

I found that the W3C's home page has a profile at http://www.w3.org/2000/08/w3c-synd/# which seems to be just a web page, so I assume that's all it has to be.