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

EN Font Header Format 11-19
Bitmap Font - Specified in PCL coordinate system dots.
Scalable Font - Specified in design units.
Figure 11-3 Character Cell - Bitmap
Orientation (UB)
Specifies the orientation of the font. All characters within the font must
have the same orientation as those specified in the font header;
otherwise they are discarded as they are downloaded.
0 = portrait (0 degrees; the orientation of the raster scan
of the printer)
1 = landscape (90 degrees counterclockwise)
2 = reverse portrait (180 degrees counterclockwise)
3 = reverse landscape (270 degrees counterclockwise)