HP 5961-0509 manual Commands that Affect LT99, 22-24The Line and Fill Attributes Group

	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

22-24The Line and Fill Attributes Group EN