Phill,
There is one general Texel Rating system, it's formula based.
That means we take the dimensions of a boat, put it in a formula and that gives the rating
But there are versions, a beachcat version and cabin cat/tri version.
The bigger cabin cat and tri's have provision for screechers etc..
And there are a couple of variants on the Texel Rating systems, for instance the Australian multihull yacht club of Queensland uses a slightly modified version of the Texel Rating.
Geert
Geert