Gnuplot.Rangetype t = | X of float * float| Y of float * float| XY of float * float * float * floatarguments are x1, x2, y1, y2
| XYZ of float * float * float * float * float * floatarguments are x1, x2, y1, y2, z1, z2
| Date of date * date| Time of time * time * timezone| Local_time of time * timeTime range in local time zone.
*)Used for constructing ranges for the X axis, Y axis or both.