This thread was about the name of INFI and its history or provenience. But however, because it comes about the steel composition, I don't think Mike Stewart knew what he was talking about.
I found in many sources all over the internet a composition like - INFI has: 0.5% carbon, 8.5% Chromium, 0.74% nickel, 0.36% vanadium 1.3% molybdenum 0.95% cobalt and 0.11% nitrogen. The rest is iron (obvious). This was (if I remember well) at some point confirmed by Jerry Busse too. The only unrevealed problem was about how the nitrogen is added and how these elements are mixed together. But the composition given by Mike Stewart's understanding seem to be totally different. I also heard that the 0.11% nitrogen usually cannot be revealed through the normal chemical inspection of the steel, being a very low amount (but it affects the properties of the steel).
Sorry I can't find all the sources at this moment, I will continue searching, for now I found in a hurry only this:
http://www.bladeforums.com/forums/showthread.php?p=5510876 (look at the fourth post in the page), but there were a lot of forums where I found a similar (or nearly similar) composition for INFI steel.