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

17-22 An Introduction to HP-GL/2 Vector Graphics EN
Notes Whenever the printer receives a Pen Down command, it produces
a dot at the current pen location. If the pen is already down when
the printer receives a command with an automatic Pen Down, the
unnecessary dot can mar your final output. For best results, include
a Pen Up (PU) command before any command with an automatic
Pen Down.
Only the portion of the pen falling within the effective window is
printed. The pen is centered on a line between the beginning and
end points, with half of the pen width falling on either side of this line.
The definition of each command tells you whether it has an automatic
pen down. If you find that part of your image is not drawn, make sure
your command sequence uses the PD command before the affected
commands.
Table 17-8 Commands That Include an Automatic Pen Down
Command Group
CI Circle The Vector Group
EA Edge Rectangle Absolute The Polygon Group
EP Edge Polygon
ER Edge Rectangle Relative
EW Edge Wedge
FP Fill Polygon
RA Fill Rectangle Absolute
RR Fill Rectangle Relative
WG Fill Wedge
LB Label The Character Group
SM Symbol Mode The Line and Fill Attributes Group