Encoding

@important Keysyms are 32-bit integers whoose 3 most significant bits are always set to zero. Thus valid keysyms are in the range 0 – 0x1fffffff = XKB_KEYSYM_MAX.

Note

Throughout this documentation, keysyms values are viewed as four bytes, numbered from most significant to least significant:

Byte 1: The most significant 8 bits: 3 zero bits and the most-significant 5 bits of the 29-bit effective value.
Byte 2: The next most-significant 8 bits
Byte 3: The next most-significant 8 bits
Byte 4: The least-significant 8 bits

Categories

There are 6 categories:

Overview

Category	Subcategory	Byte 1	Byte 2	Byte 3	Byte 4	First keysym	Last keysym
Special keysyms		`0`	`0`	`0`	`0`	`NoSymbol`
Latin-1 keysyms	ASCII non-control characters	`0`	`0`	`0`	`0x20` – `0x7e`	`space`	`asciitilde`
Latin-1 keysyms	Latin-1 Supplement	`0`	`0`	`0`	`0xa0` – `0xff`	`nobreakspace`	`ydiaeresis`
Legacy keysyms	Latin-2	`0`	`0`	`0x01`	`0x00` – `0xff`	`Aogonek`	`abovedot`
	Latin-3			`0x02`		`Hstroke`	`scircumflex`
	Latin-4			`0x03`		`kra`	`umacron`
	Kana			`0x04`		`overline`	`semivoicedsound`
	Arabic			`0x05`		`Arabic_comma`	`Arabic_sukun`
	Cyrillic			`0x06`		`Serbian_dje`	`Cyrillic_HARDSIGN`
	Greek			`0x07`		`Greek_ALPHAaccent`	`Greek_omega`
	Technical			`0x08`		`leftradical`	`downarrow`
	Special			`0x09`		`blank`	`vertbar`
	Publishing			`0x0a`		`emspace`	`cursor`
	APL			`0x0b`		`leftcaret`	`righttack`
	Hebrew			`0x0c`		`hebrew_doublelowline`	`hebrew_taf`
	Thai			`0x0d`		`Thai_kokai`	`Thai_lekkao`
	Korean			`0x0e`		`Hangul_Kiyeog`	`Korean_Won`
	Latin-5			`0x0f`
	Latin-6			`0x10`
	Latin-7			`0x11`
	Latin-8			`0x12`
	Latin-9			`0x13`		`OE`	`Ydiaeresis`
	Currency			`0x20`		`EuroSign`
Function keysyms	IBM 3270 terminals	`0`	`0`	`0xfd`	`0x00` – `0xff`	`3270_Duplicate`	`3270_Enter`
	Keyboard (XKB) Extension			`0xfe`		`ISO_Lock`	`Pointer_Drag5`
	Keyboard			`0xff`		`BackSpace`	`Delete`
Special keysyms		`0`	`0xff`	`0xff`	`0xff`	`VoidSymbol`
Unicode keysyms		`0x01`	`0x00` – `0x10`	`0x00` – `0xff`	`0x00` – `0xff`	`0x01000100`	`0x0110ffff`
Vendor keysyms	DEC, HP, misc.	`0x10`	`0x00`	`0x00` – `0xff`	`0x00` – `0xff`	`0x10000000`	`0x1000ffff`
		`0x10`	`0x01` – `0x03`			`0x10010000`	`0x1003ffff`
	OSF	`0x10`	`0x04`			`0x10040000`	`0x1004ffff`
	Sun	`0x10`	`0x05`			`0x10050000`	`0x1005ffff`
		`0x10`	`0x06` – `0x07`			`0x10060000`	`0x1007ffff`
	XFree86	`0x10`	`0x08`			`0x10080000`	`0x1008ffff`
		`0x10` – `0x1f`	`0x09` – `0xff`			`0x10090000`	`0x1fffffff`

Special keysyms

There are 2 special values: `NoSymbol` and `VoidSymbol`. They are used to indicate the absence of symbols.

Byte 1	Byte 2	Byte 3	Byte 4	Hex. value	Name
0	0	0	0	`0x00000000`	`NoSymbol`
0	255	255	255	`0x00ffffff`	`VoidSymbol`

See also: Appendix A “Special keysyms” of the X Window System Protocol.

Latin-1 keysyms

The Latin-1 keysyms occupy the range 0x0020 – 0x007E and 0x00a0 – 0x00ff and represent the ISO 10646 / Unicode characters U+0020 – U+007E and U+00A0 – U+00FF, respectively.

See also: ISO/IEC 8859-1 character encoding; Appendix A “Latin-1 keysyms” of the X Window System Protocol.

Legacy keysyms

Legacy keysyms date from the time before ISO 10646 / Unicode was available. They represent characters from a number of different older 8-bit coded character sets and have zero values for bytes 1 and 2. Byte 3 indicates a coded character set and byte 4 is the 8-bit value of the particular character within that set.

Byte 3
Value	Character set	Comment
1	Latin-2
2	Latin-3
3	Latin-4
4	Kana
5	Arabic
6	Cyrillic
7	Greek
8	Technical	Based on DEC Technical‌: add `0x880` to the original code point
9	Special	Based on DEC Special Graphics‌: add `0x980` to the original code point
10	Publishing
11	APL
12	Hebrew
13	Thai
14	Korean
15	Latin-5
16	Latin-6
17	Latin-7
18	Latin-8
19	Latin-9
32	Currency

Each character set contains gaps where codes have been removed that were duplicates with codes in previous character sets (that is, character sets with lesser byte 3 value).

Todo:: Legacy keysyms

See also: Latin-1 keysyms; Appendix A “Legacy keysyms” of the X Window System Protocol.

Function keysyms

Function keysyms represent keycap symbols that do not directly represent elements of a coded character set. Instead, they typically identify a software function, mode, or operation (e.g., cursor up, caps lock, insert) that can be activated using a dedicated key. Function keysyms have zero values for bytes 1 and 2. Byte 3 distinguishes between several 8-bit sets within which byte 4 identifies the individual function key.

Byte 1	Byte 2	Byte 3		Byte 4
Value	Value	Value	Function set	Value
0	0	253	IBM 3270 terminals	(individual function key)
		254	Keyboard (XKB) Extension
		255	Keyboard

Todo:: Function keysyms

See also: Appendix A “Function keysyms” of the X Window System Protocol.; Appendix C “New keysyms” of the XKB Protocol Specification.

Unicode keysyms

The Unicode keysyms occupy the range 0x01000100 – 0x0110FFFF and represent the ISO 10646 / Unicode characters U+0100 – U+10FFFF, respectively. The numeric value of a Unicode keysym is the Unicode code point of the corresponding character plus 0x01000000. In the interest of backwards compatibility, clients should be able to process both the Unicode keysym and the legacy keysym for those characters where both exist.

Note: Dead keys, which place an accent on the next character entered, shall be encoded as function keysyms, and not as the Unicode keysym corresponding to an equivalent combining character.; Where a keycap indicates a specific function with a graphical symbol that is also available in Unicode (e.g., an upwards arrow for the cursor up function), the appropriate function keysym should be used, and not the Unicode keysym corresponding to the depicted symbol.

See also: Appendix A “Unicode keysyms” of the X Window System Protocol.; Unicode technical website.

Vendor keysyms

Vendor keysyms are vendor-specific extentions in the range 0x10000000 – 0x1fffffff. Among these, the range 0x11000000 – 0x1100ffff is designated for keypad keysyms.

See also: Appendix A “Vendor keysyms” of the X Window System Protocol.