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

23-40 The Character Group EN
Figure 23-23Effects of Scaling on Label Direction
Labels begin at the current pen location and thus are drawn parallel to
the directional line, not necessarily on it. Also, negative parameters
have the same effect on direction as described for the DI command.
At least one parameter must not be zero. The ratio of the parameters
to each other is more important than the actual numbers. The table
below lists three common label angles produced by using ones and
zeros.
The relative size and sign of the two parameters determine the
amount of rotation. If you imagine the current pen location to be the
origin of a coordinate system for the label, you can see that the signs
of the parameters determine in which quadrant the label is in.
Table 23-19
DR Command Label Direction
DR 1,0 horizontal
DR 0,1 vertical
DR 1,1 or DI 0.7,0.7
(any parameters equal to each other)
diagonal from P1 to P2