Font Table

Groups Character Tables into named fonts and carries the metadata to identify them.

Use Cases

• Sub-font grouping - A single file can carry several related fonts, such as Regular, Bold, and Italic, each pointing at its own Character Tables.

Table Structure

Identifier

• Value: 0x04

Modifier Flags

Bit	Name	Description
0-7	—	Reserved for future use.

The Font Table has no modifier flags currently. The byte is still written, as 0x00.

Configuration Flags

Bit	Name	Description
0-7	—	Reserved for future use.

The Font Table has no configuration flags currently, and therefore no configuration values. The byte is still written, as 0x00.

Table Links

Bit	Name	Description
0	link_character_tables	This table links to one or more Character Tables.
1-7	—	Reserved for future use.

Link Arrays

Name	Type	Condition	Description
character_tables	Vec<u8>	If link_character_tables is enabled.	Length byte followed by that many Character Table indices this font table may reference.

Record Fields

Each record contains the following fields in order:

Field	Type	Condition	Description
name	CString	Always present.	Human-readable font name.
author	CString	Always present.	Author, manufacturer, or credits for the font.
version	u8	Always present.	Revision number of this font,
font_type	u8	Always present.	Style of this font (0 = Regular, 1 = Bold, 2 = Italic).
character_table_indexes	Vec<u8>	Always present.	Length byte followed by that many Character Table indices this font may access and use.

Record Layout Examples

Example 1: Minimal record

An unnamed, uncredited font drawing from a single Character Table.

Byte	Field	Binary	Hex	Description
1	name	00000000	00	Empty name, terminator only
2	author	00000000	00	Empty author, terminator only
3	version	00000001	01	Version 1
4	font_type	00000000	00	0 = Regular
5	character_table_indexes	00000001	01	Array length = 1
6	character_table_indexes	00000000	00	Uses Character Table 0

Example 2: Typical record

The font Toys by Nice, linking one Character Table.

Byte	Field	Binary	Hex	Description
1	name	01010100	54	T
2	name	01101111	6F	o
3	name	01111001	79	y
4	name	01110011	73	s
5	—	00000000	00	Null terminator ends name
6	author	01001110	4E	N
7	author	01101001	69	i
8	author	01100011	63	c
9	author	01100101	65	e
10	—	00000000	00	Null terminator ends author
11	version	00000001	01	Version 1
12	font_type	00000000	00	0 = Regular
13	character_table_indexes	00000001	01	Array length = 1
14	character_table_indexes	00000000	00	Uses Character Table 0

Example 3: Non-ASCII metadata and multiple Character Tables

The font Toys by Nicé, a bold variant drawing from two Character Tables. The author's last code point needs two UTF-8 bytes.

Byte	Field	Binary	Hex	Description
1	name	01010100	54	T
2	name	01101111	6F	o
3	name	01111001	79	y
4	name	01110011	73	s
5	—	00000000	00	Null terminator ends name
6	author	01001110	4E	N
7	author	01101001	69	i
8	author	01100011	63	c
9	author	11000011	C3	é (U+00E9), byte 1 of 2
10	author	10101001	A9	é (U+00E9), byte 2 of 2
11	—	00000000	00	Null terminator ends author
12	version	00000010	02	Version 2
13	font_type	00000001	01	1 = Bold
14	character_table_indexes	00000010	02	Array length = 2
15	character_table_indexes	00000000	00	Uses Character Table 0
16	character_table_indexes	00000010	02	Uses Character Table 2

Complete Table Example

The following byte sequence defines a Font Table holding two fonts, a Regular and a Bold. Between them they use the two Character Tables the table links to:

Byte	Binary	Hex	Description
1	00000100	04	Table identifier for Font Table
2	00000000	00	Modifier flags: none set
3	00000000	00	Configuration flags: none set
4	00000001	01	Table links: link_character_tables enabled
5	00000010	02	Character table array length = 2
6	00000000	00	Link to Character Table at index 0
7	00000001	01	Link to Character Table at index 1
8	00000010	02	Record count = 2 fonts
9	01010100	54	Font 0: name = T
10	01101111	6F	Font 0: name = o
11	01111001	79	Font 0: name = y
12	01110011	73	Font 0: name = s
13	00000000	00	Font 0: name terminator
14	01001110	4E	Font 0: author = N
15	01101001	69	Font 0: author = i
16	01100011	63	Font 0: author = c
17	01100101	65	Font 0: author = e
18	00000000	00	Font 0: author terminator
19	00000001	01	Font 0: version = 1
20	00000000	00	Font 0: font_type = 0 (Regular)
21	00000001	01	Font 0: character table array length = 1
22	00000000	00	Font 0: uses Character Table 0
23	01010100	54	Font 1: name = T
24	01101111	6F	Font 1: name = o
25	01111001	79	Font 1: name = y
26	01110011	73	Font 1: name = s
27	00000000	00	Font 1: name terminator
28	01001110	4E	Font 1: author = N
29	01101001	69	Font 1: author = i
30	01100011	63	Font 1: author = c
31	01100101	65	Font 1: author = e
32	00000000	00	Font 1: author terminator
33	00000001	01	Font 1: version = 1
34	00000001	01	Font 1: font_type = 1 (Bold)
35	00000001	01	Font 1: character table array length = 1
36	00000001	01	Font 1: uses Character Table 1