You can use graphic scripts to add extra lines to your graphs. For example line built using
Line({X Origin(), Y Origin()}, {X Origin() + X Range(), Y Origin() + Y Range()});
will go from bottom left to top right and you can replace X Origin()... and so on with your own values as needed
Names Default To Here(1);
dt = open("$SAMPLE_DATA/Big Class.jmp");
gb = dt << Graph Builder(
Variables(X(:weight), Y(:height), Overlay(:sex)),
Elements(Points(X, Y, Legend(9)))
);
Report(gb)[FrameBox(1)] << Add Graphics Script(
Pen Color("Blue");
Pen Size(1);
Line({X Origin(), Y Origin()}, {X Origin() + X Range(), Y Origin() + Y Range()});
);
-Jarmo