HP LaserJet 4100 HP PCL/PJL reference (PCL 5 Printer Language) - Technical Ref - Page 117

CI, Circle This command draws the circumference of a circle using the specified radius and chord angle. If you want a filled circle, refer to the WG or PM commands. CI radius[,chord angle;] Parameter Format Functional Range radius current units -230 to 230 - 1 chord angle clamped real 0.5° to 180° Default no default 5° The CI command includes an automatic pen down. When a CI command is received, the pen lifts, moves from the center of the circle (the current pen location) to the starting point on the circumference, lowers the pen, draws the circle, then returns with the pen up to the center of the circle. After the circle is drawn, the previous pen up/down status is restored. To avoid leaving a dot at the center of the circle, move to and from the circle's center with the pen up. z Radius - Measured from the current pen location. Coordinates are interpreted in current units: as user-units when scaling is on; as plotter units when scaling is off. z Chord Angle - Specifies the chord angle used to draw the arc. The default is a chord angle of 5°. Refer to the Arc Absolute (AA) command discussion, earlier in this chapter, for an explanation of the chord angle. Each chord of the circle is drawn using the currently defined line type, width, and attributes. (Refer to Chapter 22, The Line and Fill Attributes Group, for more information.) Do not use an adaptive (negative) line type to draw a circle, as the printer attempts to draw a complete pattern for every chord (72 with the default chord angle). Always use isotropic scaling in drawings that contain circles, unless you want your circles to "stretch" with aspect ratio changes of the drawing (anisotropic scaling may produce an ellipse). For more information, refer to Chapter 19 for a scaling discussion and for the Scale (SC) command description. EN CI, Circle 20-25