Reading around for other things I came across this: Re:://en.wikipedia.org/wiki/Classification_of_finite_simple_groups#Statement_of_the_classification_theorem """ Theorem: Every finite simple group is isomorphic to one of the following groups: * a member of one of three infinite classes of such, namely: * the cyclic groups of prime order, * the alternating groups of degree at least 5, * the groups of Lie type * one of 26 groups called the "sporadic groups" * the Tits group (which is sometimes considered a 27th sporadic group). """ So the Tits group is not one of the infinite families, and it's a finite simple group, so why isn't it fully and properly classed as one of the sporadic groups? What is a sporadic group if not just a finite simple group that's not one of the infinite families? Colour me puzzled. Colin -- Mathematicians are like Frenchmen: whatever you say to them they translate into their own language and forthwith it is something entirely different. -- Johann Wolfgang von Goethe 1749-1842