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

22-24 The Line and Fill Attributes Group EN
A zero line type (0) draws only a dot at the X,Y coordinates for AA,
AR, AT, CI, PA, PD, PR, and RT commands. Zero pen down values
and zero length lines also produce dots. A dot is a one plotter unit
long vector, drawn using the current line end and pen width. (Dots
within lines are drawn at the correct angle, but zero length vectors
are drawn along the user’s current X-axis.)
Negative line types (-1 - -8) are adaptive line types. The pattern
length is automatically adjusted so that each line contains one or
more complete patterns.
Line patterns are composed of alternate pen down and pen up
moves which are percentages of the pattern length (the first
percentage is always pen down).
99 (LT99) restores the previous line type (and residue if it is a
fixed-line type).
Note If a solid line type is selected (LT;) when the LT99 command is issued,
and the current pen position has not changed, the previously selected
line type can be invoked using LT99. LT99 is ignored when a
non-solid line type is in effect, or if the pen is in a different position
than when the previous non-solid line ended. An example using this
command is to print a line in a non-solid line type, followed by a
rectangle in solid black; beginning at the end point of the previous
line, use LT99 to print another line in the previous non-solid line type.
Sending any of the following commands while plotting with a solid line
type clears the previous line type and a subsequent (LT99) has no
effect:
Table 22-12 Commands that Affect LT99
Command Group
AC,Anchor Corner The Line and Fill
LA,Line Attributes Attributes Group
LT,Line Type
(except (LT) and (LT99) )
PW,Pen Width
RF,Raster Fill Definition