HP 4 FAMILY - Manual (Page 74)

Data Segment Size
The Data Segment Size indicates the number of bytes in
the immediately following Data Segment. The size of this
field is 4 bytes for Font Format 16 fonts, and 2 bytes for
Font Format 15 fonts. The rest of the data segments are
identical for both font formats.
Galley Character Segment
If an application requests a character that does not exist
within the current font, the printer checks the Galley
Character Segment for a substitute character to print
instead. The Galley Character Segment specifies the
character codes of the substitute characters to be printed.
A different galley character can be specified for different
regions of the symbol set. For example, this segment can
be set up so that an asterisk prints when a non-existent
character is selected in the region 0x81 - 0x9F, and a
question mark for characters in the region 0xE0-0xFC.
Byte 15 (MSB) 8 7 (LSB) 0 Byte
0 GC (18243) 1
2
4 Data Segment Size (6*n+6) * 3
5
6 Format = 0 7
8 Default Galley Character 9
10 Number of Regions (n) 11
12 Region #1 Upper Left Character Code 13
14 Region #1 Lower Right Character Code 15
16 Region #1 Galley Character 17
. . . . . .
6*n+6 Region #n Upper Left Character Code 6*n+7
6*n+8 Region #n Lower Right Character Code 6*n+9
6*n+10 Region #n Galley Character 6*n+11
* This segment is for Font Format 16. The Data Segment Size field for Font Format 16
fonts is 4 bytes; the segment for Font Format 15 fonts is identical except the Data
Segment Size field is 2 bytes instead.
2-38 Printer-Specific Differences