HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part II

20-10 The Vector Group EN
Note Do not use an adaptive line type when drawing arcs with small chord
angles. The printer attempts to draw the complete pattern in every
chord (there are 72 chords in a circle using the default chord angle).
z XCenter, YCenter — Specify the absolute location of the center
of the arc. (The center of the arc is the center of the circle that
would be drawn if the arc was 360 degrees.)
z Coordinates are interpreted in current units: as user-units when
scaling is on; as plotter units when scaling is off. If current scaling
is not isotropic, the arc drawn is elliptical rather than circular.
z Sweep Angle — Specifies in degrees the angle through which
the arc is drawn. A positive angle is drawn in a positive direction
(angle of rotation); a negative angle is drawn in the negative
direction.
z Chord Angle — Specifies the chord angle used to draw the arc.
The default is a chord angle of 5 degrees. The chord angle
specifies, in degrees, the maximum angle created when lines
from each end of the chord intersect the center point of the circle
(see drawing below). The smaller the chord angle, the smoother
the curve.
Figure 20-7 Chord Angle