HP 4 FAMILY - Manual (Page 79)

The Typeface String Segment will be invalid if the Data
Segment Size declared in the Data Segment Size field is
larger or smaller than required for substitute string length,
or if the Data Segment Size is an odd number of bytes. If
the segment is invalid, the font download will be ignored.
Typeface String Segments can be downloaded with any
Font Format 15 or Font Format 16 font, regardless of font
type.
The following tables are examples of Typeface String
Segments for two downloaded fonts. The first is for MS
Mincho, and has the embedded font name flag set to true.
The second is for MS Gothic, and has the embedded font
name flag set to false.
Printer-Specific Differences 2-43