john huerta and i were thinking about projective light cones last night (in connection with g2 incidence geometry) and we guessed that the tangent space of a point x of one can be naturally identified with "x perp, mod x" ... which vaguely reminded me of the same formulation arising in other contexts... particularly in symplectic geometry, where however i don't offhand see an interpretation as a tangent space... maybe there is such an interpretation, but it doesn't seem to work the same way as in the "quadratic" case... i also can't remember whether i've seen this formulation in the quadratic case before.... ???... hmm, also, what about when x is null of higher dimension, or non-null?? ...