HP 4 FAMILY - Manual (Page 137)

Vertical Writing with
Proportional Fonts
The Character Text Path Direction command was
introduced with the HP LaserJet 4PJ printer to allow users
to vertically rotate Asian fonts which were dual pitched.
That is, the single-byte characters were half-width and the
other characters were full-width.
An algorithm was implemented to determine whether or
not to counter-rotate characters when using the
vertical-rotated printing mode of the Character Text Path
Direction command. A character is rotated if the glyph is
full-width; otherwise, the character is not rotated.
Since the introduction of the LaserJet 4PJ, many vendors
have produced proportional versions of their Asian fonts.
Thus, the algorithm described above is no longer
appropriate for determining character rotation.
A new method to explicitly enumerate which characters
should be counter-rotated in the font is being introduced
with HP LaserJet 5 and 5M printers. The new method
consists of adding an optional font segment to Font Format
16. The optional segment, which is called the Vertical
Exception (VE) segment, has the following form:
UBYTE[2] SEGMENT ID = ’VE’
UBYTE Format = 0
(other values reserved)
UBYTE NumRanges = N
UINT16 Range1FirstCode
UINT16 Range1LastCode
•
•
•
UINT16 RangeNFirstCode
UINT16 RangeNLastCode
Printer-Specific Differences 2-101