OPML is just a contents page

I was just talking to my good friend Marjolein on skype and we were talking about how people are focusing on OPML as a great way of describing someone's attention.

I was trying to explain our Personal Relevancy engine and how it's Attention Profile differed from straight OPML when out of nowhere a quick metaphor popped into my head. I thought I'd share.

OPML is like a contents page
Touchstone indexes the whole book