??for derek...

??something about non-split signatures... particularly "physical" penrose diagram case...

??something about "cartanian dual of lightlike curve in 2+1 conformal spacetime" and legendrian and "generalized legendrian" submanifods ... ??and so forth...

??what about something about "pfaffian system of diff eqs" here ??? ... or something... and so forth ... ???something about the "non-trivial tangent cone" case ... ???or something ... and so forth ... ???....

??something about dimension of coadjoint grassmanian ... ???and so forth ... ??something about long root subalgebra???....

???what _about_ something about idea of... "trying to get incidence geometry and invariant distributions and so forth to work essentially the same way for all real forms, just by sharing the same root diagram" ? ... ??? .... or something ... ???...