HP PCL 5 Reference Manual page 235

Continuation (B)
This is the second (and last) byte of every character data block
header. It specifies whether the following data is the first (0) data
block of a new character definition, or a continuation (1) block for a
character definition which has already been received by the printer.
Because the value field in a Character Definition command is limited
to 32767 bytes, characters whose byte count exceed this must be
sent in two or more blocks.
Descriptor Size (UB)
This is the first byte of the character descriptor. It specifies the size
of the character descriptor in bytes. The descriptor size used by the
HP LaserJet printer family for bitmap fonts is 14.
Class (UB)
Specifies the format of the character data. For bitmap fonts only
values 1 and 2 are used, as described below.
Table 11-38
* These are described later in this chapter.
EN
Value Class
1 Bitmap
2 Compressed Bitmap
3* Contour (Intellifont Scalable)
4* Compound Contour (Intellifont Scalable)
15* TrueType Scalable
Character Descriptor Formats 11-53