??a1 real cartan torus .... ? as "genuine" aspect-ratio adjustment group ... ???? ....

?? generic flag ordered pair .... 2 points ... first as infinity, second as 0 ... so projective line becomes affine and then linear ... ??re-scaling of this linear line as adjusting aspect-ratio ??? .... ??? horizontal and vertical as dual ?? ... ??? symplectic structure ??? ....

?? so cartan torus of symplectic group here as "corresponding" linear group ... ??? ....

?? "cartan torus" ... ?? "maximal torus" .... ???? ....