VT240, VT241 are graphics? what does it mean?

[Carlo Pisani via cctalk]

hi
so, in a description of DEC terminals, I read "VT240 and VT241 are
graphics terminals, supporting Digital’s ReGIS graphics and Tektronix
vector graphics"

what does it mean? which kind of graphics? Can they draw lines?

I am googling for "Digital’s ReGIS graphics" and "Tektronix vector
graphics", but I have only found dead links =(