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

11-48 Soft Font Creation EN
Character Definitions
Following the font header, the individual characters must be defined.
Every PCL character definition contains a character descriptor and a
body of character data. The character definition always consists of
one or more character data blocks. Each character data block begins
with its own header. The character data block header always has a
size of 2 bytes.
The first data block of a character definition must always have a
character descriptor immediately after its 2-byte header.
Character descriptor/data is downloaded using the Character
Definition command preceding every character (see Character
Definition Command).
Notes A unique character code, using the Character Code command, must
be designated prior to the download of a character descriptor and
data. If the font being downloaded already contains a character with
this code, the existing character is deleted during the download of the
character descriptor and data.
Unless otherwise specified, inappropriate values in a character
descriptor field invalidates the character download process; a
character is not created, and the associated descriptor and data
are discarded.
An undefined printable character is one which is in the printable
range of the font type but has no defined pattern. Attempts to print
an undefined printable character from a font result in the execution
of a Space control code.
Character descriptor fields identified as “reserved” should be set to
zero.
If the total byte count of the character descriptor and data exceeds
32767 bytes, then the remaining data must be sent using the
continuation descriptor.