libxkbcommon: The XKB keymap text format, V1 and V2

libxkbcommon 1.13.1 Library implementing the XKB specification for parsing keyboard descriptions and handling keyboard state

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The XKB keymap text format, V1 and V2

This document describes the following keymap formats, as implemented by libxkbcommon:

XKB_KEYMAP_FORMAT_TEXT_V1

  The classic XKB text format, as generated by xkbcomp -xkb. See XKB Compatibility for further information.

XKB_KEYMAP_FORMAT_TEXT_V2

  Xkbcommon extensions of the classic XKB text format, incompatible with X11. See XKB Compatibility for further information.

See also
  For an overview of the role of this format, please see “XKB the keyboard keymap configuration”.
  For examples of keymaps in this format, please see “User-configuration”. For further examples see xkeyboard-config, the standard database of keyboard configuration data.

Note
  Due to the complexity of the format, this document is still is construction. Some additional resources are:
  - Ivan Pascal’s XKB documentation
  - An Unreliable Guide to XKB Configuration
  - The X Keyboard Extension: Protocol Specification
  - How to enhance XKB configuration
  - ArchWiki XKB page

# Terminology

Keycode

  Code that identifies a physical key on a keyboard.

  - Raw keycodes are the numeric identifiers used as input in XKB. They are the result of the low-level processing of the data that keyboards send to a computer. For instance 36 may represent the return key.
  - XKB keycodes are symbolic names assigned to raw keycodes in order to facilitate their mapping to symbols. For instance the keycode for the return key is the abbreviation RTRN.

  See xkb_keycodes for further details.

Symbols

  A keysym (short for “key symbol”) is a numeric encoding of a symbol on the cap of a key.

  Some keysyms have a canonical name for convenience. The complete list of canonical names is defined in xkbcommon/xkbcommon-keysyms.h.

  Common types of keysyms are:

  - A character: e.g. a and A for Latin scripts, alpha “α” and ALPHA “Α” for Greek, etc.

  - A dead key: e.g. dead_grave and dead_diaeresis, corresponding respectively to the grave accent and the diaeresis diacritics.

    A dead key is a special kind of key that does not generate a character by itself, but modifies the character generated by the key struck(s) immediately after.

  - A modifier⁠: e.g. Shift_L, Control_R, Caps_Lock. See hereinafter.
  - A system action: e.g. the arrow Left, Pause, Escape, F1.
  See also
    xkb_symbols for further details on binding Keysyms to keycodes.
    [Keysym syntax][Keysyms]
Modifier

  A modifier key is a key that modifies the effect of other keys: e.g. Shift, Control, Caps Lock, etc.

  The state of a modifier key (active/inactive) is encoded as a modifier index (or modifier bit or simply modifier) and has an associated unique name.

  For historical reasons, modifiers are divided in two categories:

  Real modifiers

    They are the 8 predefined (AKA core, X11) modifiers (see usual modifiers hereinafter).

    Real modifiers ensure backward compatibility: indeed they are the actual bits used to compute the levels and are communicated via the API of xkbcommon.

    Some are generic modifiers (Mod[1-5]) that do not have a conventional interpretation and are the motivation of the introduction of virtual modifiers.

  Virtual modifiers
    They are the modifiers that are not predefined.

  Each modifier has an associated encoding. In keymaps compatible with X11, the encoding can be interpreted as a mapping to one or multiple real modifier. Real modifiers map to themselves: they are canonical modifiers. See the “Modifiers encoding” section for further information.

  The following table lists the usual modifiers present in the standard keyboard configuration. Note that this is provided for information only, as it may change depending on the user configuration.

  Modifier | Type | Usual mapping | Comment
  --- | --- | --- | ---
  Shift | Real | Shift (fixed) | The usual Shift
  Lock | Real | Lock (fixed) | The usual Caps Lock
  Control | Real | Control (fixed) | The usual Control
  Mod1 | Real | Mod1 (fixed) | Not conventional
  Mod2 | Real | Mod2 (fixed) | Not conventional
  Mod3 | Real | Mod3 (fixed) | Not conventional
  Mod4 | Real | Mod4 (fixed) | Not conventional
  Mod5 | Real | Mod5 (fixed) | Not conventional
  Alt | Virtual | Mod1 | The usual Alt
  Meta | Virtual | Mod1 | The legacy Meta key
  NumLock | Virtual | Mod2 | The usual NumLock
  Super | Virtual | Mod4 | The usual Super/GUI
  LevelThree | Virtual | Mod5 | ISO level 3, aka AltGr
  LevelFive | Virtual | Mod3 | ISO level 5

  A modifier key can report its state in one of the following 3 ways:

  Depressed
    Active while depressed; e.g. the usual Shift.
  Latched
    Activated when pressed and deactivated after the next non-modifier key press.
  Locked
    Activated when pressed and deactivated when pressed again; e.g. the usual Caps Lock.

  See modifiers declaration and binding for further details.

Shift Level

  A key may produce different results depending of the active modifiers: e.g. for a Latin script, pressing the key A produces “a” and holding Shift while pressing A produces “A”.

  This various results are organized in an ordered list; the index of each entry is called a shift level or simply level. By convention the lowest level is the result when no modifier is active. Example for the key A on a latin script keyboard:

  Level | Description | Keysym | Active key modifiers
  --- | --- | --- | ---
  1 | Lower case letters | a | None
  2 | Upper case letters. | A | Shift
  3 | Alternative lower case letters | ae | AltGr
  4 | Alternative upper case letters | AE | Shift + AltGr

  A key shift level is the logical state of a key corresponding to the current shift level it used.

  Key shift levels are derived from the modifiers states, but not necessarily in the same way for all keys. For example, for Latin script the Caps Lock modifier selects the level 2 for alphabetic keys such as A but has no effect on a numeric key.

  There are groups of keys with the same characteristics: letters, punctuation, numeric keypad, etc. The meaning of their levels is identical and thus can be shared: this generalization is called a key type (see hereinafter).

Key type

  A key type defines the levels available for a key and how to derive the active level from the modifiers states. Examples:

  - ONE_LEVEL: the key has only one level, i.e. it is not affected by any modifiers. Example: the modifiers themselves.
  - TWO_LEVEL: the key has two levels:
    - Level 1: default level, active when the Shift modifier is not active.
    - Level 2: level activated with the Shift modifier.
  - FOUR_LEVEL: see the example in the previous section.

  See xkb_types for further details.

Layout

  A mapping of keycodes to symbols, actions and key types.

  A user who deals with multiple languages may need two or more different layouts: e.g. a layout for Arabic and another one for English. In this context, layouts are called groups in XKB, as defined in the standard ISO/IEC 9995.

  Layouts are ordered and identified by their index. Example:

  - Layout 1: Arabic
  - Layout 2: English

Key Action

  In XKB world, a key action defines the effect a key has on the state of the keyboard or the state of the display server. Examples:

  - Change the state of a modifier.
  - Change the active group.
  - Move the mouse pointer.

  See the section “Key actions” for further details.

Indicator

  A keyboard indicator is a mean to report a specific aspect of the keyboard state.

  Physical indicator
    Typically a labelled LED on the keyboard, e.g. “Caps Lock” and “Num Lock”.
  Logical indicator

    A customizable derived state of the keyboard. Its changes creates events that can be monitored.

    There are two categories:

    - Real indicators are those associated to a physical indicator. For example, the “Caps Lock” logical modifier controls the corresponding physical LED.

      Because indicators are customizable, if one misses a “Num Lock” LED, one could define instead the “Caps Lock” indicator to activate its LED when the “Num Lock” modifier is active.

    - Virtual indicators are not associated to a physical indicator. Their effect is only visible for programs monitoring them.

    Note that the meanings of real and virtual is slightly different than the one used for modifier.

  See: `xkb_keycodes` to define indicators and `xkb_compat` to define their effects.

Keymap

  The complete definition of the mapping of raw keycodes to symbols and actions. It fully defines the behavior of a keyboard.

  Depending of the context, a keymap may refer to:

  - the software object defined and managed by libxkbcommon;
  - the text configuration used to create this software object.

  See Keymap components and xkb_keymap for further details.

Keyboard configuration database
  A database that provides the keymap components. *nix OSs uses the standard database xkeyboard-config. One may extend this database with custom layouts: see “User-configuration” for further details.

# Introduction to the XKB text format

The XKB text format uses a syntax similar to the C programming language. Note that the similarity with C stops here: the XKB text format is only a configuration format and is not intended for programming.

The XKB text format is used to configure a keyboard keymap, which is introduced in “XKB the keyboard keymap configuration”. It has the following two main use cases, illustrated in the diagram hereinafter:

- Server: Load a keymap from the keymap configuration database, then handle input events by updating the keyboard state. The keymap is assembled from an RMLVO configuration and its corresponding KcCGST components files.

  See also
    xkb_keymap::xkb_keymap_new_from_names2
    xkeyboard-config for the implementation of the standard Keymap Creation configuration database.
    “User-configuration” to add a custom layout or option.

- Client: Load the active keymap from the server, then handle update events sent by the server. The complete keymap is directly available in a self-contained file.

  See also
    xkb_keymap::xkb_keymap_new_from_string

  XKB text format use cases

## XKB file

There are two kinds of files for the XKB text format:

Keymap file

  A file with the complete description of the keymap object. It is the kind of file that the server sends to the client (see the diagram above). Its top-level structure consists of the xkb_keymap block.

Keymap component file
  A file with the description of a particular KcCGST component. It is the kind of file that the server uses to assemble a keymap file. Its top-level structure consists of a single type of keymap sections. A component file may contain multiple such sections.

## Keymap components

Keymap components are described with keymap sections. They are grouped in keymap component files to form a keyboard configuration database.

Keymap component
  A part of the keymap object. The set of keymap components is referred as KcCGST. They are presented in the table hereinafter.
Keymap section
  A part of the keymap text configuration dedicated to one of the keymap components.
Component folder
  A folder in the keymap configuration database, dedicated to files with partial definitions of the same keymap section.

Keymap components
Component | Section in a keymap | Folder in a keymap configuration database | Description
--- | --- | --- | ---
Key codes | xkb_keycodes | keycodes | A translation of the raw key codes from the keyboard into symbolic names.
Compatibility | xkb_compat | compat | A specification of what internal actions modifiers and various special-purpose keys produce.
(Geometry) | xkb_geometry | geometry | A description of the physical layout of a keyboard. Attention This legacy feature is not supported by xkbcommon.
Key symbols | xkb_symbols | symbols | A translation of symbolic key codes into actual key symbols (keysyms).
Key types | xkb_types | types | Types describe how a pressed key is affected by active modifiers such as Shift, Control, Alt, etc.

## Comments

Comments are introduced following either // or # until the end of the line.

## Literals

String literal

  A string is surrounded by double quotes: “`"`”. The following escape sequences are supported:

  Escape sequence | Meaning
  --- | ---
  \\ | Backslash “\”
  \" | Double quote “"”
  \b | Backspace
  \e | Escape
  \f | Form feed
  \n | Line feed (newline)
  \r | Carriage return
  \t | Horizontal tabulation
  \v | Vertical tabulation
  \ + octal number | Corresponding ASCII character: \1 → SOH, \42 → ". Up to 4 octal digits 0‥7 are parsed. The result must fit into a byte.
  \u{ + hexadecimal number + } | \u{NNNN} produce the corresponding Unicode code point U+NNNN, encoded in UTF-8. Supported code points are in the range U+0001‥U+10FFFF.

  Note
    The string encoding is unspecified and not validated, but for best results, stick to ASCII.
  Since
    <1.9.0: Octal escape sequences accept up to 3 digits.
    1.9.0: Octal escape sequences accept up to 4 digits. Added `\"` and \u{NNNN} escape sequences.
Number literal

  A number can be written in three forms:

  - decimal integer: 1, 123, etc.
  - decimal floating-point number: 1.23, etc.
  - hexadecimal integer: prefixed with 0x: 0x123, 0xff, 0xAB, etc.

## Keysyms

Keysyms may be written in multiple ways:

Name

  Keysym names are defined in xkbcommon/xkbcommon-keysyms.h; remove the XKB_KEY_ prefix to get the name.

  Example: the keysym 0xffbe = XKB_KEY_F1 has the name F1.

Unicode

  The Unicode syntax Unnnn denotes a keysym whose corresponding character is the Unicode code point U+nnnn, where nnnn is an hexadecimal number in the range 0x100 .. 0x10ffff. The resulting keysym value is 0x01000000 + nnnn.

  Example: U1F3BA has value 0x0101F3BA and corresponds to the code point U+1F3BA: ‘🎺’ (TRUMPET).

String literal

  A keysym or list of keysyms can be written as a string literal, with the following semantics:

  1. The string must be encoded in UTF-8.
  2. If the encoding is invalid, it raises a syntax error.
  3. If the string expands to 0 Unicode code point, the resulting keysym is NoSymbol.
  4. If the string expands to 1 Unicode code point, the resulting keysym is the output of xkb_utf32_to_keysym.

  5. Otherwise the string expands to a list { ... } with each Unicode code point converted via xkb_utf32_to_keysym.

     Note
       This is only possible where multiple keysyms is valid, e.g. in the key symbols.

     Examples:

  Keysym string | Keysym name | Keysym value
  --- | --- | ---
  "" | NoSymbol | 0x0000
  "a" | a | 0x0061
  "ü" | udiaeresis | 0x00dc
  "🎺" | U1F3BA | 0x0101F3BA
  "g̃" | {g, combining_tilde} | {0x0101F3BA, 0x01000303}

  See also
    Keysym strings
  Since
    1.9.0
Numeric value

  A keysym can be written directly with its numeric value: e.g. 0x61 is a.

  This syntax is mostly useful in the following use cases:

  - the corresponding keysym has no associated name nor is in the Unicode range;
  - the corresponding keysym has/had a name but it is not supported in all the ecosystem;
  - keymap serialization by tools.
  Note
    Digits 0 .. 9 have a special treatment because they are interpreted as names, not values. E.g. 1 is the keysym with name 1 and value 0x31.
    The previous special case does not apply to integers values in range 0 .. 9 that are written with 2+ characters: e.g. 01 and 0x1 are both interpreted as the unnamed keysym with value 0x01, not the keysym named 1 and with value 0x31.
  Warning
    Do not use this syntax to manually write keymap files unless there is no other option: it is the least human-friendly syntax.

## Keywords

The following table presents the keywords used in the format. They are case-sensitive.

Keyword | Use
--- | ---
action | Action of an interpret statement
alias | Keycode alias
alphanumeric_keys | Section flag
alternate_group | Section flag
alternate | Merge mode qualifier for include statements
augment | Merge mode qualifier for include statements
default | Section flag
function_keys | Section flag
group | TODO
hidden | Section flag
include | Include statement
indicator | Indicator statement in either the keycode section or the compatibility section
interpret | Interpret statement
key | Key statement
keypad_keys | Section flag
keys | Legacy geometry element
logo | Legacy geometry element
mod_map | Alias of modifier_map
modifier_keys | Section flag
modmap | Alias of modifier_map
modifier_map | Real modifier bindings
outline | Legacy geometry element
overlay | Legacy geometry element
override | Merge mode qualifier for include statements
partial | Section flag
replace | Merge mode qualifier for include statements
row | Legacy geometry element
section | Legacy geometry element
shape | Legacy geometry element
solid | Legacy geometry element
text | Legacy geometry element
type | Key type statement
virtual_modifiers | Virtual modifiers mappings
virtual | Flag for the indicator statement
xkb_compat_map | Alias of xkb_compatibility_map
xkb_compat | Alias of xkb_compatibility_map
xkb_compatibility_map | Declare a compatibility section
xkb_compatibility | Alias of xkb_compatibility_map
xkb_geometry | Declare a geometry section
xkb_keycodes | Declare a keycodes section
xkb_keymap | Declare a keymap block
xkb_layout | Declare a legacy layout compound section
xkb_semantics | Declare a legacy semantics compound section
xkb_symbols | Declare a symbols section
xkb_types | Declare a key types section

## Built-in settings

There are many built-in settings; they are explained in the following relevant sections.

These settings are case-insensitive, e.g. the following strings denote the same key word: SETMODS, SetMods, setMods and setmods.

## Merge modes

Each statement has a merge mode property that defines how to handle conflicts with previous statements. This property can be set explicitly by prefixing the statement with one of the merge modes presented hereinafter.

augment

  If two declarations conflict, update the properties which are explicitly defined in the new declaration, only if they were implicit in the old declaration.

  key <A> { [a , NoSymbol , ae ] };
  augment key <A> { [Greek_alpha, Greek_ALPHA, NoSymbol, AE] };
  // Result
  key <A> { [a , Greek_ALPHA, ae , AE] };
override

  If two declarations conflict, update only the properties which are explicitly defined in the new declaration.

  Note
    Override is the default merge mode.
  key <A> { [a , NoSymbol , ae ] };
  // Explicit merge mode
  override key <A> { [Greek_alpha, Greek_ALPHA, NoSymbol, AE] };
  // Result
  key <A> { [Greek_alpha, Greek_ALPHA, ae , AE] };
  key <A> { [a , NoSymbol , ae ] };
  // Implicit merge mode is override
  key <A> { [Greek_alpha, Greek_ALPHA, NoSymbol, AE] };
  // Result
  key <A> { [Greek_alpha, Greek_ALPHA, ae , AE] };
replace

  If two declarations conflict, ignore the old declaration and use the new one.

  key <A> { [a , NoSymbol , ae ] };
  replace key <A> { [Greek_alpha, Greek_ALPHA, NoSymbol, AE] };
  // Result
  key <A> { [Greek_alpha, Greek_ALPHA, NoSymbol, AE] };
alternate

  Legacy merge mode for keycodes. Its purpose is to allow to assign the same key name to multiple key codes, which is not allowed otherwise. This is unfortunately poorly documented and not used in xkeyboard-config. The xkblib specification implies that this was part of the overlay functionality, which is currently not supported by libxkbcommon.

  Warning
    This merge mode is not supported by libxkbcommon and is ignored.

## The include mechanism

### Syntax

Statements of the form:

// Implicit section name: use the default map
include "<PATH>"
// Explicit section name
include "<PATH>(<SECTION_NAME>)"

will merge data from another section of the same type, possibly located in another file. Note that the statement does not have a trailing semicolon.

If no section name is provided, the default map is looked up.

The path is usually relative to its corresponding directory in a XKB configuration: e.g. given the configuration directory <XKB>, files of section type xkb_symbols are looked up in <XKB>/symbols. Since 1.11, the paths can also be absolute or use %-expansion:

%%
  A literal %.
`%H`
  The value of the $HOME environment variable.
`%S`

  The main system-installed XKB directory of the corresponding component (usually /usr/share/X11/xkb/<component>).

  This enables e.g. to override a system file using User-configuration with the exact same name:

  // File: ~/.config/xkb/symbols/de
  xkb_symbols "basic" {
  // Include the system file /usr/share/X11/xkb.
  //
  // Note that it is not be possible to use `include "de(basic)"` because
  // it would create an include *loop*.
  include "%S/de(basic)"
  // Override the system file entries
  key <AB01> { [z, Z] };
  key <AD06> { [y, Y] };
  }
`%E`
  The extra system-wide XKB directory of the corresponding component (usually /etc/xkb/<component>).

Warning
  Absolute paths and %-expansion are supported by libxkbcommon but not by the legacy X11 tools.

The include keyword uses the default merge mode. The following keywords can be used instead to use the corresponding explicit merge modes:

- augment
- override
- replace

Multiple files can be included using the same statement. They are separated using one of the following merge mode prefixes:

- ‘|’ selects the augment merge mode.
- ‘+’ selects the override merge mode (default).
- ‘^’ selects the replace merge mode.

The following example illustrates the complete syntax:

// Default merge mode, 1 file with an implicit section name
include "<PATH>"
// Augment merge mode, 1 file with an implicit section name
augment "<PATH>(<SECTION_NAME>)"
// Absolute path and %-expansion
include "/usr/share/X11/xkb/symbols/pc"
include "%S/pc"
// Override merge mode, 2 files: a first file with an implicit section name merged
// using the augment mode with a second file with an explicit section name
override "<PATH_1>|<PATH_2>(<SECTION_NAME>)

### Processing

Important
  Since xkbcommon 1.9.0 the included files are processed in isolation and are not affected by the parent file (e.g. defaults), except for the virtual modifiers indices.
  Since xkbcommon 1.9.0 local merge modes are not propagated outside the section scope, i.e. an included file does not leaks its local merge modes to its parent.

The statement is processed as follow:

1. Set PARENT as the current section containing the include statement.
2. Set INCLUDED_MERGE_MODE to the merge mode corresponding to the keyword.
3. Initialize an empty section as INCLUDED.
4. Select the first file as the current file to process.
5. Set CURRENT_MERGE_MODE to the merge mode corresponding to the current file merge mode prefix.

6. The current file path is searched sequentially in the [XKB configuration path list]:

   - If a section name is provided, select the first exact match of file + section.
   - If no section name is provided, select the first explicit default map in matched files, else if no exact match was found in the path list, then fallback to the first implicit default map as a weak match.

   Then if no match is found, raise an error; else go to the next step.

7. The current file is processed and results in the CURRENT section.
8. The INCLUDED section is merged with the CURRENT section using the merge mode CURRENT_MERGE_MODE.
9. If they are more files, select the next file as the current file and go to step 5). Else go to step 10).
10. Once all files have been processed, merge PARENT with INCLUDED using the merge mode INCLUDED_MERGE_MODE.

### Example: include path list

Let’s illustrate using the following XKB configuration path list:

1. /home/<USER>/.config/xkb: user configuration directory (see User-configuration).
2. /usr/share/X11/xkb: system directory.

The relevant directory structure is:

- /home/<USER>/.config/xkb
  - symbols
    - es
    - my_own_file
- /usr/share/X11/xkb
  - symbols
    - es
    - it

Then the following file:

xkb_symbols {
include "it" // Exists only in system directory
include "my_own_file" // Exists only in user directory
include "es" // Exists in both user and system directory
};

is equivalent to:

xkb_symbols {
include "/usr/share/X11/xkb/symbols/it"
include "/home/<USER>/.config/xkb/symbols/my_own_file"
include "/home/<USER>/.config/xkb/symbols/es"
};

### Example: simple include

Given the following files:

- symbols/A

  xkb_symbols {
  key <A> { [a, A, ae, AE] };
  include "B(S2)"
  };

- symbols/B

  // This section is not used (does not match)
  xkb_symbols "S1" {
  key <B> { [b, B] };
  };
  // This section will be included (match the included section name)
  xkb_symbols "S2" {
  key <A> { [Greek_alpha, Greek_ALPHA] };
  key <B> { [Greek_beta , Greek_BETA ] };
  };

the resulting section in A will be:

xkb_symbols {
// Key overridden: mix of old + new
key <A> { [Greek_alpha, Greek_ALPHA, ae, AE] };
// New key
key <B> { [Greek_beta , Greek_BETA ] };
};

### Example: merge modes

Given the same file symbols/B of the previous example, the following section:

Input | Output
--- | ---
xkb_symbols { key <A> { [a, A, ae, AE] }; augment "B(S2)" }; | xkb_symbols { // Key unchanged key <A> { [a, A, ae, AE] }; // New key key <B> { [Greek_beta , Greek_BETA] }; };
xkb_symbols { key <A> { [a, A, ae, AE] }; replace "B(S2)" }; | xkb_symbols { // Key replaced key <A> { Greek_alpha, Greek_ALPHA] }; // New key key <B> { [Greek_beta , Greek_BETA ] }; };
xkb_symbols { key <A> { [a, A, ae, AE] }; // Two files merged together with the merge mode // augment, then the result is merged this the // statement above using the override merge mode include "B(S1)|B(S2)" }; | xkb_symbols { // Key overridden: mix of old + new key <A> { [Greek_alpha, Greek_ALPHA, ae, AE] }; // New key; "B(2)" had no effect with the // merge mode augment "|" key <B> { [b, B] }; };

# The “xkb_keymap” block

A keymap file consists of a single top-level xkb_keymap block, under which are nested the following sections:

`xkb_keycodes`
  A translation of the hardware/evdev scancodes from the keyboard into XKB symbolic keycodes.
`xkb_types`
  A specification of the modifier mask, target level and preserved modifiers various modifiers combination produce.
`xkb_compat`
  A specification of what actions various special-purpose keys produce.
`xkb_symbols`
  A translation of symbolic key codes into actual symbols and actions.

Overview of a keymap file:

xkb_keymap {
xkb_keycodes "XXX" {
// ...
}
xkb_types "XXX" {
// ...
};
xkb_compatibility "XXX" {
// ...
};
xkb_symbols "XXX" {
// ...
};
};
xkb_keymap
Opaque compiled keymap object.

Since
  1.9.0 All the component are optional.

Remarks
  The XKB file format historically supported the following compound section types:
  - xkb_semantics: must contain a xkb_compat section and can contain a xkb_types section.
  - xkb_layout: must contain xkb_keycodes, xkb_types and xkb_symbols sections and can contain xkb_geometry section.
  - xkb_keymap: must contain xkb_keycodes, xkb_compat, xkb_types and xkb_symbols sections and can contain xkb_geometry section.
  Since such distinction is purely semantic and would have niche use cases lost to history, these compound sections are treated equally as xkb_keymap in libxkbcommon.

# Section flags

A section can have various flags applied to it, separated by whitespaces:

    partial alphanumeric_keys
    xkb_symbols "basic" {
        ...
    }

## Generic flags

The possible flags are:

`partial`
  Indicates that the map doesn’t cover a complete keyboard.
`default`

  Marks the symbol map as the explicit default map in the file. If no map is marked as a default, the first map in the file is the implicit default. Only one section can be marked as the default in each file.

`hidden`
  Variant that can only be used internally.

## Symbols flags

Additionally, xkb_symbols may also have the following flags:

`alphanumeric_keys`
  Indicates that the map contains alphanumeric keys.
`modifier_keys`
  Indicates that the map contains modifier keys: Control, Shift, Alt, Meta, etc.
`keypad_keys`
  Indicates that the map contains keypad keys.
`function_keys`
  Indicates that the map contains function keys: F1, F2, etc.
`alternate_group`
  Indicates that the map contains keys for an alternate group.

If no *_keys flags are supplied, then the symbols section is assumed to cover a complete keyboard.

At present, except for default (see: default map), none of the flags affect key processing in libxkbcommon, and only serve as metadata.

# The “xkb_keycodes” section

This is the simplest section type, and is the first one to be compiled. The purpose of this is mostly to map between the hardware/evdev scancodes and XKB keycodes. Each key is given a name by which it can be referred to later, e.g. in the symbols section.

## Keycode statements

Statements of the form:

    <TLDE> = 49;
    <AE01> = 10;

The above would let 49 and 10 be valid keycodes in the keymap, and assign them the names TLDE and AE01 respectively. The format <WXYZ> is always used to refer to a key by name.

The naming convention <AE01> is based on the standard ISO/IEC 9995-1. It denotes the position of the key in the keyboard grid. It means: the main alphanumeric section (A), row E and column 01.

The following figure illustrates the grid on a staggered standard US QWERTY keyboard. <AE01> corresponds to the key 1.

\ 99 \ 00 \ 01 \ 02 \ 03 \ 04 \ 05…
\ \ \ \ \ \ \
-----------------------------------------
E \ \ ^ \ 1 \ 2 \ 3 \ 4 \ 5…
------------------------------------------
D \ Tab \ Q \ W \ E \ R \ T…
-------------------------------------------
C \Caps \ A \ S \ D \ F \ G…
--------------------------------------------
B \Shift \ Z \ X \ C \ V \ B…
---------------------------------------------
A \Ctrl\GUI \Alt \Space…
----------------------------------------------

In the common case this just maps to the evdev scancodes from /usr/include/linux/input.h, e.g. the following definitions:

    #define KEY_GRAVE            41
    #define KEY_1                2

correspond to the ones above. Similar definitions appear in the xf86-input-keyboard driver. Note that in all current keymaps there’s a constant offset of 8 (for historical reasons).

Note that contrary to xkbcommon, the X11 protocol supports keycodes only up to 255. Therefore, when interfacing with X11, keymaps and applications using keycodes beyond 255 should expect warnings.

If there’s a conflict, like the same name given to different keycodes, or same keycode given different names, it is resolved according to the merge mode which applies to the definitions.

## Alias statements

Statements of the form:

    alias <MENU> = <COMP>;

Allows to refer to a previously defined key (here <COMP>) by another name (here <MENU>). Conflicts are handled similarly to keycode statements.

## LED name statements

Statements of the form:

    indicator 1 = "Caps Lock";
    indicator 2 = "Num Lock";
    indicator 3 = "Scroll Lock";

Assigns a name to the keyboard LED (AKA indicator) with the given index. The LED may be referred by this name later in the compat section and by the user.

Todo
  virtual flag

# The “xkb_types” section

This section is the second to be processed, after xkb_keycodes. However, it is completely independent and could have been the first to be processed (it does not refer to specific keys as specified in the xkb_keycodes section).

This section defines key types, which, given a key and a keyboard state (i.e. modifier state and group), determine the shift level to be used in translating the key to keysyms. These types are assigned to each group in each key, in the xkb_symbols section.

Key types are called this way because, in a way, they really describe the “type” of the key (or more correctly, a specific group of the key). For example, an ordinary keymap will provide a type called KEYPAD, which consists of two levels, with the second level being chosen according to the state of the Num Lock (or Shift) modifiers. Another example is a type called ONE_LEVEL, which is usually assigned to keys such as Escape; these have just one level and are not affected by the modifier state. Yet more common examples are TWO_LEVEL (with Shift choosing the second level), ALPHABETIC (where Caps Lock may also choose the second level), etc.

## How key types work

Key types define a mapping between the modifiers and shift levels. Key types have four parameters:

Shift level names
  Declare shift levels. Mainly for documentation.
Modifiers filter
  Declare what modifiers should be taken into account in the mapping.
Modifiers mapping
  Lookup table to translate modifiers combinations into shift levels.
Modifiers preservation
  Tweak the computation of consumed modifiers.

Key types are used to compute:

- the shift level: see xkb_state::xkb_state_key_get_level().
- the consumed modifiers: see xkb_state::xkb_state_key_get_consumed_mods() and xkb_state::xkb_state_key_get_consumed_mods2().

The following diagram presents an overview of theses computations:

Use of key types to compute shift level and consumed modifiers

## Type definitions

Statements of the form:

    type "FOUR_LEVEL" { ... }

The above would create a new type named FOUR_LEVEL. The body of the definition may include statements of the following forms:

### “level_name” statements

    level_name[Level1] = "Base";

Mandatory for each level in the type.

Gives each level in this type a descriptive name. It isn’t used for anything.

Note: A level may be specified as Level[1-8] or just a number (can be more than 8).

### “modifiers” statement

    modifiers = Shift+Lock+LevelThree;

Mandatory, should be specified only once.

A mask of real and virtual modifiers. These are the only modifiers being considered when matching the modifier state against the type. The other modifiers, whether active or not, are masked out in the calculation.

### “map” entry statements

    map[Shift+LevelThree] = Level4;

Should have at least as many mappings as there are levels in the type.

If the active modifiers, masked with the type’s modifiers (as stated above), match (i.e. equal) the modifiers inside the map[] statement, then the level in the right hand side is chosen. For example, in the above, if in the current keyboard state the Shift and LevelThree modifiers are active, while the Lock modifier is not, then the keysym(s) in the 4th level of the group will be returned to the user.

### “preserve” statements

    map[Shift+Lock+LevelThree] = Level5;
    preserve[Shift+Lock+LevelThree] = Lock;

When a key type is used for keysym translation, its modifiers are said to be consumed in this translation. For example, in a simple US keymap, the “G” key is assigned an ordinary ALPHABETIC key type, whose modifiers are Shift and Lock; then for the “G” key, these two modifiers are consumed by the translation. This information is relevant for applications which further process the modifiers, since by then the consumed modifiers have already “done their part” and should be masked out.

However, sometimes even if a modifier had already affected the key translation through the type, it should not be reported as consumed, for various reasons. In this case, a preserve[] statement can be used to augment the map entry. The modifiers inside the square brackets should match one of the map[] statements in the type (if there is no matching map entry, one mapping to Level1 is implicitly added). The right hand side should consists of modifiers from the type’s modifiers; these modifiers are then “preserved” and not reported as consumed.

Attention
  Consuming a locked modifier does not unlock it and it can be consumed again in further keysym translations.

Note
  Remember that Keysym Transformations may affect the resulting keysym when some modifiers are not consumed.

Remarks
  preserve statements may be used to tweak keyboard shorcuts.
  Example of use of preserve to tweak Control shortcuts. Note it would require further work in order to support other modifiers.
  xkb_types {
  // ...
  type "TWO_LEVEL_PLUS_CONTROL" {
  modifiers = Shift + Control;
  map[None] = Level1;
  map[Shift] = Level2;
  map[Control] = Level3;
  map[Control+Shift] = Level4;
  // Using preserve will make Control not consumed and allow
  // applications to detect keyboard shortcuts with alternative
  // keysyms in levels 3 and 4 rather than the levels 1 and 2.
  preserve[Control] = Control;
  preserve[Control+Shift] = Control;
  level_name[Level1] = "Base";
  level_name[Level2] = "Shift";
  level_name[Level3] = "Tweaked Control";
  level_name[Level4] = "Tweaked Control + Shift";
  };
  };
  xkb_symbols {
  // ...
  // The following key would produce Greek keysym on Base and Shift levels,
  // but will produce the corresponding ASCII Latin keysyms when using Control.
  key <AC01> {
  type[Group1]="TWO_LEVEL_PLUS_CONTROL",
  [Greek_alpha, Greek_ALPHA, a, A]
  };
  };

## Key types examples

### Definitions examples

Note
  The convention is that Lock affect only “alphabetic” types. For such types, Lock “cancels” Shift by default, i.e. Shift+Lock has the same result as neither modifier. “semi-alphabetic” types have an asymmetry: their first two levels are alphabetic while the next are not.

#### Two levels

The following examples compare two basic types with two levels: TWO_LEVEL and ALPHABETIC. They differ on their handling of the Lock modifier. See the next section for an illustration with concrete layouts.

TWO_LEVEL

Definition code (source)

type "TWO_LEVEL" {
// Only care about Shift; Lock will be filter out
modifiers = Shift;
// Define mapping
map[None] = Level1; // No modifier -> level 1
map[Shift] = Level2; // Exactly Shift -> level 2
// (no map entry with Lock)
// Define level names
level_name[Level1] = "Base";
level_name[Level2] = "Shift";
};

Mapping test

Active modifiers | Filtered modifiers | Match? | Shift level
--- | --- | --- | ---
(none) | (none) | Yes | 1
Shift | Shift | Yes | 2
Lock | (none) | Yes | 1
Shift + Lock | Shift | Yes | 2

ALPHABETIC

Definition code (source)

type "ALPHABETIC" {
// Only care about Shift and Lock
modifiers = Shift + Lock;
// Define mapping
map[None] = Level1; // No modifier -> level 1
map[Shift] = Level2; // Exactly Shift -> level 2
map[Lock] = Level2; // Exactly Lock -> level 2
// Define level names
level_name[Level1] = "Base";
level_name[Level2] = "Caps";
};

Mapping test

Active modifiers | Filtered modifiers | Match? | Shift level
--- | --- | --- | ---
(none) | (none) | Yes | 1
Shift | Shift | Yes | 2
Lock | Lock | Yes | 2
Shift + Lock | Shift + Lock | No | 1

#### Four levels

The following examples compare basic types with four levels: FOUR_LEVEL, FOUR_LEVEL_SEMIALPHABETIC and FOUR_LEVEL_ALPHABETIC. They differ on their handling of the Lock modifier. See the next section for an illustration with concrete layouts.

FOUR_LEVEL

Definition code (source)

type "FOUR_LEVEL" {
modifiers = Shift + LevelThree;
map[None] = Level1;
map[Shift] = Level2;
// (no map entry with Lock)
// (no map entry with Lock)
map[LevelThree] = Level3;
map[Shift+LevelThree] = Level4;
// (no map entry with Lock)
// (no map entry with Lock)
// (no preserve entry with Lock)
// (no preserve entry with Lock)
level_name[Level1] = "Base";
level_name[Level2] = "Shift";
level_name[Level3] = "AltGr";
level_name[Level4] = "Shift AltGr";
};

Mapping test

Active modifiers | Filtered modifiers | Match? | Shift level
--- | --- | --- | ---
(none) | (none) | Yes | 1
Shift | Shift | Yes | 2
Lock | (none) | Yes | 1
Shift+Lock | Shift | Yes | 2
LevelThree | LevelThree | Yes | 3
LevelThree+Shift | LevelThree+Shift | Yes | 4
LevelThree+Lock | LevelThree | Yes | 3
LevelThree+Shift+Lock | LevelThree+Shift | Yes | 4

FOUR_LEVEL_SEMIALPHABETIC

Definition code (source)

type "FOUR_LEVEL_SEMIALPHABETIC" {
modifiers = Shift + Lock + LevelThree;
map[None] = Level1;
map[Shift] = Level2;
map[Lock] = Level2;
map[Shift+Lock] = Level1;
map[LevelThree] = Level3;
map[Shift+LevelThree] = Level4;
map[Lock+LevelThree] = Level3;
map[Shift+Lock+LevelThree] = Level4;
preserve[Lock+LevelThree] = Lock;
preserve[Shift+Lock+LevelThree] = Lock;
level_name[Level1] = "Base";
level_name[Level2] = "Shift";
level_name[Level3] = "AltGr";
level_name[Level4] = "Shift AltGr";
};

Mapping test

Active modifiers | Filtered modifiers | Match? | Shift level
--- | --- | --- | ---
(none) | (none) | Yes | 1
Shift | Shift | Yes | 2
Lock | Lock | Yes | 2
Shift+Lock | Shift+Lock | Yes | 1
LevelThree | LevelThree | Yes | 3
LevelThree+Shift | LevelThree+Shift | Yes | 4
LevelThree+Lock | LevelThree+Lock | Yes | 3
LevelThree+Shift+Lock | LevelThree+Shift+Lock | Yes | 4

FOUR_LEVEL_ALPHABETIC

Definition code (source)

type "FOUR_LEVEL_ALPHABETIC" {
modifiers = Shift + Lock + LevelThree;
map[None] = Level1;
map[Shift] = Level2;
map[Lock] = Level2;
map[Shift+Lock] = Level1;
map[LevelThree] = Level3;
map[Shift+LevelThree] = Level4;
map[Lock+LevelThree] = Level4;
map[Shift+Lock+LevelThree] = Level3;
// (no preserve entry with Lock)
// (no preserve entry with Lock)
level_name[Level1] = "Base";
level_name[Level2] = "Shift";
level_name[Level3] = "AltGr";
level_name[Level4] = "Shift AltGr";
};

Mapping test

Active modifiers | Filtered modifiers | Match? | Shift level
--- | --- | --- | ---
(none) | (none) | Yes | 1
Shift | Shift | Yes | 2
Lock | Lock | Yes | 2
Shift+Lock | Shift+Lock | Yes | 1
LevelThree | LevelThree | Yes | 3
LevelThree+Shift | LevelThree+Shift | Yes | 4
LevelThree+Lock | LevelThree+Lock | Yes | 4
LevelThree+Shift+Lock | LevelThree+Shift+Lock | Yes | 3

### Examples with standard keyboard layouts

See the detailed table of mappings

The following table compares the mappings of various key types for the modifiers Shift, Lock and LevelThree, using the standard layouts us (US English) and es (Spanish).

Key | Layout | Key type | Active modifiers | Level | Keysym | Comment
--- | --- | --- | --- | --- | --- | ---
AE01 | us | TWO_LEVEL | (none) | 1 | 1 |
Shift | 2 | exclam |
Lock | 1 | 1 | Lock filtered out
Shift + Lock | 2 | exclam | Lock filtered out
LevelThree | 1 | 1 | LevelThree filtered out
LevelThree + Shift | 2 | exclam | LevelThree filtered out
LevelThree + Lock | 1 | 1 | Modifiers LevelThree and Lock filtered out
LevelThree + Shift + Lock | 2 | exclam | Modifiers LevelThree and Lock filtered out
es | FOUR_LEVEL | (none) | 1 | 1 |
Shift | 2 | exclam |
Lock | 1 | 1 | Lock filtered out
Shift + Lock | 2 | exclam | Lock filtered out
LevelThree | 3 | bar |
LevelThree + Shift | 4 | exclamdown |
LevelThree + Lock | 3 | bar | Lock filtered out
LevelThree + Shift + Lock | 4 | exclamdown | Lock filtered out
AD01 | us | ALPHABETIC | (none) | 1 | q |
Shift | 2 | Q |
Lock | 2 | Q |
Shift + Lock | 1 | q | Lock cancelled by Shift
LevelThree | 1 | q | LevelThree filtered out
LevelThree + Shift | 1 | q | LevelThree filtered out
LevelThree + Lock | 2 | Q | LevelThree filtered out
LevelThree + Shift + Lock | 1 | q | LevelThree filtered out, Lock cancelled by Shift
es | FOUR_LEVEL_SEMIALPHABETIC | (none) | 1 | q |
Shift | 2 | Q |
Lock | 2 | Q |
Shift + Lock | 1 | q | Lock cancelled by Shift
LevelThree | 3 | at |
LevelThree + Shift | 4 | Greek_OMEGA |
LevelThree + Lock | 3 | at | Lock does not affect LevelThree combos
LevelThree + Shift + Lock | 4 | Greek_OMEGA | Lock does not affect LevelThree combos
AD05 | us | ALPHABETIC | (none) | 1 | t |
Shift | 2 | T |
Lock | 2 | T |
Shift + Lock | 1 | t | Lock cancelled by Shift
LevelThree | 1 | t | LevelThree filtered out
LevelThree + Shift | 1 | t | LevelThree filtered out
LevelThree + Lock | 2 | T | LevelThree filtered out
LevelThree + Shift + Lock | 1 | t | LevelThree filtered out, Lock cancelled by Shift
es | FOUR_LEVEL_ALPHABETIC | (none) | 1 | t |
Shift | 2 | T |
Lock | 2 | T |
Shift + Lock | 1 | t | Lock cancelled by Shift
LevelThree | 3 | tslash |
LevelThree + Shift | 4 | Tslash |
LevelThree + Lock | 4 | Tslash |
LevelThree + Shift + Lock | 3 | tslash | Lock cancelled by Shift

# The “xkb_compat” section

This section is the third to be processed, after xkb_keycodes and xkb_types.

## Interpret statements

Statements of the form:

    interpret Num_Lock+Any { ... }
    interpret Shift_Lock+AnyOf(Shift+Lock) { ... }

The `xkb_symbols` section (see below) allows the keymap author to perform, among other things, the following things for each key:

- Bind a sequence of actions, like SetMods or LockGroup, to the key. Actions, like symbols, are specified for each level of each group in the key separately.
- Add a virtual modifier to the key’s virtual modifier mapping (vmodmap).
- Specify whether the key should repeat or not.

However, doing this for each key (or level) is tedious and inflexible. Interpret’s are a mechanism to apply these settings to a bunch of keys/levels at once.

Each interpret specifies a condition by which it attaches to certain levels. The condition consists of two parts:

- A keysym. If the level has a different (or more than one) keysym, the match fails. Leaving out the keysym is equivalent to using the special value Any or the NoSymbol keysym, which always matches successfully.

- A modifier predicate. The predicate consists of:

  - A mask of real modifiers: a +-separated list of modifiers or the special value all, which denotes all the modifiers.

    The modifiers are matched against the key’s modifier map (modmap).

  - A matching operation, that is one of the following:
    - AnyOfOrNone – The modmap must either be empty or include at least one of the specified modifiers.
    - AnyOf – The modmap must include at least one of the specified modifiers.
    - Any – Alias for AnyOf(all).
    - NoneOf – The modmap must not include any of the specified modifiers.
    - AllOf – The modmap must include all of the specified modifiers (but may include others as well).
    - Exactly – The modmap must be exactly the same as the specified modifiers.

  Leaving out the predicate is equivalent to using AnyOfOrNone(all). Leaving out just the matching condition is equivalent to using Exactly.

An interpret may also include useModMapMods = level1; – see below.

If a level fulfils the conditions of several interprets, only the most specific one is used:

- A specific keysym will always match before a generic NoSymbol condition.
- If the keysyms are the same, the interpret with the more specific matching operation is used. The above list is sorted from least to most specific.
- If both the keysyms and the matching operations are the same (but the modifiers are different), the first interpret is used.

As described above, once an interpret “attaches” to a level, it can bind an action to that level, add one virtual modifier to the key’s vmodmap, or set the key’s repeat setting. You should note the following:

- The key repeat is a property of the entire key; it is not level-specific. In order to avoid confusion, it is only inspected for the first level of the first group; the interpret’s repeat setting is ignored when applied to other levels.
- If one of the above fields was set directly for a key in xkb_symbols, the explicit setting takes precedence over the interpret.

The body of the statement may include statements of the following forms (all of which are optional):

### “useModMapMods” statement

    useModMapMods = level1;

When set to level1, the interpret will only match keysyms which are on the first level of the first group of the keys. This can be useful in conjunction with e.g. a virtualModifier statement, because virtualModifier is an attribute of the key rather than a specific level.

Note: the other possible value is any and is the default value.

See virtual modifier map for further information.

### “virtualModifier” statement

    virtualModifier = NumLock;

Add this virtual modifier to the key’s vmodmap. The given virtual modifier must be declared at the top level of the file with a virtual_modifiers statement, e.g.:

    virtual_modifiers NumLock;

See virtual modifier map for further information.

### “repeat” statement

    repeat = True;

Set whether the key should repeat or not. Must be a boolean value.

### “action” statement

    action = LockMods(modifiers=NumLock);

Bind this action to the matching levels. See key actions for the list of available key actions.

Since 1.9.0, it is also possible to assign a sequence of actions, mirroring the feature used in the key statement.

    action = {SetMods(modifiers=NumLock),SetGroup(group=2)};

## LED map statements

Statements of the form:

    indicator "Shift Lock" { ... }

This statement specifies the behavior and binding of the LED (AKA indicator) with the given name (“Shift Lock” above). The name should have been declared previously in the xkb_keycodes section (see LED name statement), and given an index there. If it wasn’t, it is created with the next free index.

The body of the statement describes the conditions of the keyboard state which will cause the LED to be lit. It may include the following statements:

### “modifiers” statement

    modifiers = ScrollLock;

If the given modifiers are in the required state (see below), the LED is lit.

### “whichModState” statement

    whichModState = Latched+Locked;

Can be any combination of:

- base, latched, locked, effective
- any (i.e. all of the above)
- none (i.e. none of the above)
- compat (legacy value, treated as effective)

This will cause the respective portion of the modifier state (see struct xkb_state) to be matched against the modifiers given in the modifiers statement.

Here’s a simple example:

    indicator "Num Lock" {
        modifiers = NumLock;
        whichModState = Locked;
    };

Whenever the NumLock modifier is locked, the Num Lock LED will light up.

### “groups” statement

    groups = All - group1;

If the given groups are in the required state (see below), the LED is lit.

### “whichGroupState” statement

    whichGroupState = Effective;

Can be any combination of:

- base, latched, locked, effective
- any (i.e. all of the above)
- none (i.e. none of the above)

This will cause the respective portion of the group state (see struct xkb_state) to be matched against the groups given in the groups statement.

Note: the above conditions are disjunctive, i.e. if any of them are satisfied the LED is lit.

## Set default values

One may change the default values of the following statements:

- interpret: use interpret.FIELD = VALUE;
- indicator: use indicator.FIELD = VALUE;
- actions: use ACTION_NAME.FIELD = VALUE;. E.g. setMods.clearLocks= True;.

# The “xkb_symbols” section

This section is the fourth to be processed, after xkb_keycodes, xkb_types and xkb_compat.

Statements of the form:

    xkb_symbols "basic" {
        ...
    }

Declare a symbols map named basic. Statements inside the curly braces only affect the symbols map.

## Name statements

Statements of the form:

    name[Group1] = "US/ASCII";
    groupName[1] = "US/ASCII";

Gives the name “US/ASCII” to the first group of symbols. Other groups can be named using a different group index (ex: Group2), and with a different name. A group must be named.

group and groupName mean the same thing, and the Group in Group1 is optional.

## Key statement

Statements of the form:

    key <AD01> { ... };

defines the key description of the keycode <AD01> and is the main type of record of the xkb_symbols section. The possible keycodes are defined in the xkb_keycodes section.

A key description consists of:

Groups

  Each key may have one or more associated groups. Each group can be configured with the following parameters:

  - Type
  - Symbols
  - Actions
Additional attributes

  These attributes are usually set via the `xkb_compat` section, but may be also set directly:

  - Virtual modifiers
  - Repeat

Warning
  Using multiple groups in symbols files is not recommended, because some tools rely on the assumption that an xkb_symbols section only affect a single group. It is fine with a keymap file though.

Note
  In what follows we assume the common use case with a single group, which benefits from a special syntax. See the section Multiple groups for the general syntax.

### Symbols

The main part of the key description is the symbols table. It maps shift levels to keysyms, e.g.:

key <AD01> { [ q, Q ] }; // Level 1 → `q`, Level 2 → `Q`

Symbols are named using the symbolic names from the xkbcommon/xkbcommon-keysyms.h file. See the keysym syntax for further information. A group of symbols is enclosed in brackets and separated by commas. Each element of the symbol arrays corresponds to a different shift level. In this example, the symbol (keysym) XKB_KEY_q for level 1 and XKB_KEY_Q for level 2. These levels are configured by the key type, presented in the next section.

Remarks
  Remember that Keysym Transformations may affect the resulting keysym when some modifiers are not consumed.
  Trailing NoSymbol are dropped.

As an extension to the XKB legacy format, libxkbcommon supports multiple key symbols and actions per level (the latter since version 1.8.0):

key <AD08> { [ {i, j} , U0132 ] }; // IJ Dutch digraph
key <AC05> { [ {g, U0303} , {G, U0303} ] }; // G̃ Guarani letter
key <AB05> { [ {U0644, U0627}, {U0644, U0622}] }; // ⁧لا⁩ ⁧لآ⁩ Arabic Lam-Alef ligatures decomposed
key <AD01> { [ {c, U2019, h} , {C, U2019, h} ] }; // C’H Breton trigraph

In this example, the keycode <AD08> produces two symbols on level 1 (XKB_KEY_i and XKB_KEY_j) and one symbol (Unicode keysym U0132 for “Ĳ”) on level 2. <AD08> and <AD01> produce letters that have no precomposed code point in Unicode. Key <AB05> avoids the need of using Compose.

Since 1.9.0, UTF-8-encoded strings may be used to denote a list of keysyms corresponding to the encoded Unicode code points. E.g. the previous example can be also written more intuitively as:

key <AD08> { [ "ij" , "Ĳ" ] }; // IJ Dutch digraph
key <AC05> { [ "g̃" , "G̃" ] }; // G̃ Guarani letter
// NOTE: We use U+200E LEFT-TO-RIGHT MARK in order to display the strings in
// in the proper order.
key <AB05> { [ "لا"‎ , "لآ"‎ ] }; // ⁧لا⁩ ⁧لآ⁩ Arabic Lam-Alef ligatures decomposed
key <AD01> { [ "c’h", "C’h" ] }; // C’H Breton trigraph

When no actions are explicitly given, they are automatically filled thanks to interpretations from the compat section. In the following example,

    key <LCTL> { [ { Control_L, ISO_Group_Shift } ] };

is equivalent to (given standard definitions from xkeyboard-config):

    key <LCTL> {
        symbols[1] = [ { Control_L,                  ISO_Group_Shift    } ],
        actions[1] = [ { SetMods(modifiers=Control), SetGroup(group=+1) } ]
    };

When using this example with e.g. two layouts fr,us (respectively Azerty and Qwerty layouts), typing Control + A in the first layout fr will in fact result in Control + Q, because the actions are run sequentially: first set the base modifiers to Control, then switch to the second layout while Control is pressed.

Remarks
  Given a level, keysyms and actions may have a different count. For instance, the following would achieve the same effect than the former example with only 1 keysym, but it requires to use 2 explicit actions:
  key <LCTL> {
  symbols[1] = [ Control_L ],
  actions[1] = [ { SetMods(modifiers=Control), SetGroup(group=+1) } ]
  };

Note
  There are some limitations with this extension:

  - For now, at most one action of each following categories is allowed per level:

    - modifier actions: SetMods, LatchMods, LockMods;
    - group actions: SetGroup, LatchGroup, LockGroup.

    Some examples of actions combination:

    - SetMods + SetGroup: ok
    - SetMods + SetMods: error
    - SetMods + LockMods: error
    - SetMods + LockGroup: ok
  - Multiple actions are only supported from version 1.8.0.

Since
  1.8.0: When using multiple keysyms or actions per level, NoSymbol and NoAction() are dropped in order to normalize the levels:
  // Before normalization
  key <> { [{NoSymbol}, {a, NoSymbol}, {NoSymbol,b}, {a, NoSymbol, b}] };
  // After normalization
  key <> { [NoSymbol, a, b, {a, b}] };

Since
  1.9.0: Trailing NoSymbol and NoAction() are dropped in groups:
  // Before normalization
  key <> { [a, NoSymbol] };
  // After normalization
  key <> { [a] };
  This affects the automatic key type detection.

Since
  1.9.0: Added support for keysyms and actions lists of length 0 and 1, respectively {} and {a}. {} is equivalent to the corresponding NoSymbol or NoAction().

Warning
  Keymaps containing multiple key symbols per level are not supported by the various X11-related tools (setxkbmap, xkbcomp, etc.).

### Type

Each key has a key type set per group. This key type is defined in the `xkb_types` section. Its associated shift levels are used to index the symbols table presented in the previous section.

A key type is set using the following syntax:

key <AD01> {
type[Group1] = "TWO_LEVEL", // Type
[q, Q] // Symbols
};

The name of the key type is enclosed between double quotes.

The key type may be omitted and will default to:

- key.type global defaults, if set.
- a standard type using the following heuristic:
  - 1 keysym: ONE_LEVEL
  - 2 keysyms:
    - if the two keysyms are letter and the first is lower case and the other upper case, then ALPHABETIC;
    - if one of the keysyms is numpad, then KEYPAD else TWO_LEVEL.
  - 3 or 4 keysyms (a missing 4th keysym is set to NoSymbol):
    - if the first two keysyms are letters and the first is lower case and the other upper case:
      - if the last two keysyms are letters and the first is lower case and the other upper case then FOUR_LEVEL_ALPHABETIC;
      - else FOUR_LEVEL_SEMIALPHABETIC.
    - if one of the first two keysyms is numpad, then FOUR_LEVEL_KEYPAD;
    - else FOUR_LEVEL.

Commented examples for inferred types:

// 1 to 2 keysyms
key <LFSH> { [Shift_L] }; // Type: ONE_LEVEL
key <AE01> { [1, exclam] }; // Type: TWO_LEVEL
key <AD01> { [q, Q] }; // Type: ALPHABETIC
key <KP1> { [KP_End, KP_1] }; // Type: KEYPAD
// Edge case: this is consider alphabetic, although
// the lower case does not correspond to the upper case.
key <AD01> { [q, N] }; // Type: ALPHABETIC
// 3 to 4 keysyms
key <AE01> { [1, exclam, bar] }; // Type: FOUR_LEVEL
key <AE01> { [1, exclam, bar, exclamdown] }; // Type: FOUR_LEVEL
key <AD01> { [q, Q, at] }; // Type: FOUR_LEVEL_SEMIALPHABETIC
key <AD01> { [q, Q, at, Greek_OMEGA] }; // Type: FOUR_LEVEL_SEMIALPHABETIC
key <AD05> { [t, T, tslash, Tslash] }; // Type: FOUR_LEVEL_ALPHABETIC
// The inferred type is `FOUR_LEVEL`, but using `LevelThree+Lock`
// will produce `Q`, because of the keysyms transformations and
// the corresponding internal capitalization processing.
key <AE01> { [1, exclam, q, Q] }; // Type: FOUR_LEVEL
// Won’t work, because there is no heuristic for more than 4 keysyms
// It will trigger the warnings XKB-183 and XKB-516 and default to ONE_LEVEL,
// ignoring all the keysyms but the first one.
key <AD01> {[q, Q, at, any, masculine, U2642]};
// Will work as expected
key <AD01> {
type[Group1] = "EIGHT_LEVEL_SEMIALPHABETIC",
[q, Q, at, any, masculine, U2642]
};

### Actions

Note
  This is usually not set explicitly but via the interpret mechanism by using the action statement in the `xkb_compat` section.

Example: Set the modifier action of the key <LALT> manually.

key <LALT> {
symbols[Group1]=[Alt_L],
actions[Group1]=[SetMods(modifiers=modMapMods)]
};

For further details see key actions.

Remarks
  Trailing NoAction() are dropped.

### Multiple groups

Each group represents a list of symbols mapped to a keycode:

    name[Group1]= "US/ASCII";
    name[Group2]= "Russian";
    ...
    key <AD01> { [ q, Q ],
                 [ Cyrillic_shorti, Cyrillic_SHORTI ] };

A long-form syntax can also be used:

    key <AD01> {
        symbols[Group1]= [ q, Q ],
        symbols[Group2]= [ Cyrillic_shorti, Cyrillic_SHORTI ]
    };

Groups can also be omitted, but the brackets must be present. The following statement only defines the Group3 of a mapping:

    key <AD01> { [], [], [ q, Q ] };

Warning
  Using multiple groups in symbols files is not recommended, because some tools rely on the assumption that an xkb_symbols section only affect a single group. It is fine with a keymap file though.

### Virtual modifiers

Note
  This is usually not set explicitly but via the interpret mechanism by using the virtualModifier statement from the `xkb_compat` section.

Remarks
  When setting a modifier action, it is required to declare the corresponding virtual modifier using a virtual_modifiers statement.

Example: Set the virtual modifier of the key <LALT> to Alt.

// Declare the virtual modifier that will be used
virtual_modifiers Alt;
key <LALT> {
virtualModifiers = Alt,
[ Alt_L ]
};

See virtual modifier map for further information.

### Repeat

Note
  This is usually not set explicitly but via the interpret mechanism by using the repeat statement in the `xkb_compat` section.

Example: make the <LALT> key not repeating.

key <LALT> {
repeat = False,
[ Alt_L ]
};

## Real Modifier map

Bind a real modifier to a key, e.g.:

// Bind the real modifier `Control` to the key `<LCTL>` and/or the first key with
// the keysym `Control_L`.
modifier_map Control { <LCTL>, Control_L };

See real modifier map for further information.

## Set default values

One may change the default values of the following statements:

- key: use key.FIELD = VALUE;. E.g. key.type = "ALPHABETIC";.
- action: use ACTION_NAME.FIELD = VALUE;. E.g. setMods.clearLocks= True;.

# Modifiers declaration and binding

## Real and virtual modifiers

Modifiers are a particularly tricky part of XKB and deserve their own section. For historical reasons they are divided in two categories:

Real modifier

  They are the 8 predefined (AKA core, X11) modifiers:

  Name | Index/Bit | Mask | Description
  --- | --- | --- | ---
  Shift | 0 | 0x01 | Used to type upper case letters of bicameral scripts; keyboard shortcuts
  Lock | 1 | 0x02 | Used to type upper case letters of [bicameral scripts]: “Caps Lock”
  Control | 2 | 0x04 | Used in keyboard shortcuts
  Mod1 | 3 | 0x08 | Generic modifier 1
  Mod2 | 4 | 0x10 | Generic modifier 2
  Mod3 | 5 | 0x20 | Generic modifier 3
  Mod4 | 6 | 0x40 | Generic modifier 4
  Mod5 | 7 | 0x80 | Generic modifier 5

  They are the modifiers defined in the core X11 protocol. They are qualified as “real”, because in the XKB protocol they denote the bits that encode the modifiers state. See Modifiers encoding for further information.

  Since they are predefined, they require no explicit declaration and have a fixed encoding.

Virtual modifier

  They are the modifiers that are not predefined. They require an explicit declaration and their encoding is user-defined.

  Note that in X11, the maximum of virtual modifiers is 16 (see XkbNumVirtualMods), whereas up to 24 virtual modifiers can be defined in libxkbcommon, for a total of 32 modifiers (real + virtual).

## Modifiers declarations

Virtual modifiers must be declared before their first use with the virtual_modifiers statement:

- Declare a single modifier:
  virtual_modifiers MyModifier;
- Declare multiple modifiers using a comma-separated list:
  virtual_modifiers M1, M2, M3.

Furthermore, it is possible to set the explicit modifier encoding with the following syntax:

- Use a real modifier mask:
  // Single modifier: real modifier
  virtual_modifiers M1 = Mod3;
  // Single modifier: using mask as a plus-separated list
  virtual_modifiers M2 = Mod4+Mod5;
  // Multiple modifiers
  virtual_modifiers M1 = Mod3, M2 = Mod4+Mod5;
- Use a numeric mask:
  virtual_modifiers M1 = 0x20;
  virtual_modifiers M2 = 0xC0;
  virtual_modifiers M1 = 0x20, M2 = 0xC0;
- Use none, an alias for 0:
  virtual_modifiers M1 = none;
  // Equivalent to: M1 = 0;

This can be done in the xkb_types, xkb_compat and xkb_symbols sections.

## Modifiers key bindings

Each key has two modifiers maps:

Real modifier map

  List the real modifiers associated to the key.

  It is used as a compatibility layer for the X11 core protocol and to apply interpretations.

  See Setting the real modifier map for further information.

Real modifier map

  List the virtual modifiers associated to the key.

  It is used to set the implicit encoding of virtual modifiers.

  See Setting the virtual modifier map for further information.

### Setting the real modifier map

The real modifier map is set in the xkb_symbols section using the modifier_map statement:

- Bind directly to a keycode, e.g.:
  // Bind `Mod1` to the keycode <LALT>.
  modifier_map Mod1 { <LALT> };

- Bind indirectly via a keysym, e.g.:

  // Bind `Mod1` looking up for the keysym `Alt_L`
  modifier_map Mod1 { Alt_L };

  Indirect bindings require to be resolved to a single direct bindings. Given a keysym, there can be multiple keys that generate it, so the corresponding key is chosen following this order:

  1. by lowest group in which the keysym appears,
  2. by lowest level,
  3. by lowest key code.
- Bind using a comma-separated list of keycodes and keysyms:
  // Bind `Mod1` diretly to keycode <LALT> and indirectly via the keysym `Alt_L`
  modifier_map Mod1 { <LALT>, Alt_L };

Note
  A key can be associated to at most one real modifier.

There is also a special entry, None, that enable deleting a previous entry:

modifier_map None { <LALT> };

Note
  None must use the exact same target (keycode or keysym) in order to delete the corresponding previous entry:
  xkb_symbols {
  key <LALT> { [Alt_L] };
  modifier_map Mod1 { <LALT> };
  // Does *not* delete previous entry (expected keycode, got keysym)
  modifier_map None { Alt_L };
  // *Does* delete previous entry (correct expected keycode)
  modifier_map None { <LALT> };
  };

### Setting the virtual modifier map

The virtual modifier map can be set in 2 ways:

- Directly in the xkb_symbols section using the virtualModifiers key property:
  xkb_symbols {
  // Virtual modifiers must be declared before use
  virtual_modifiers Alt;
  key <LALT> {
  // Explicit virtual modifier map
  virtualModifiers = Alt,
  ...
  };
  };
- Indirectly using interpretations in xkb_compat and the corresponding xkb_symbols keysyms:
  xkb_compat {
  // Virtual modifiers must be declared before use
  virtual_modifiers Alt, Super;
  interpret Alt_L {
  // Bind the virtual modifier…
  virtualModifier = Alt;
  // … independently of the group and level (default)
  useModMap = AnyLevel;
  };
  interpret Super_L {
  // Bind the virtual modifier…
  virtualModifier = Super;
  // … only if the keysym is on the first level of the first group
  useModMap = Level1;
  };
  };
  xkb_symbols {
  // Successful bindings
  key <LALT> { [Alt_L] };
  key <LALT> { [No,Symbol, Alt_L] }; // independent of group and level
  key <LALT> { [], [NoSymbol, Alt_L] }; // independent of group and level
  key <LWIN> { [Super_L] };
  // Unsuccessful bindings
  key <LWIN> { [NoSymbol, Super_L] }; // requires first level
  key <LWIN> { [], [Super_L] }; // requires first group
  };

## Modifiers encoding

Each modifier has an associated 32 bit mask used to encode it in the keyboard state. The keyboard state represents active modifiers with the bitwise OR of the encoding of each active modifiers.

Note
  Display servers may use a different encoding in their protocols:
  - Wayland protocol: use the same 32-bit encoding as libxkbcommon and support its full range of modifiers.
  - X11 protocol: use a 8-bit encoding. It supports only using real modifiers to encode virtual modifiers.

Important
  - Real modifiers have a fixed predefined encoding.
  - Virtual modifiers have a user-defined encoding.

Virtual modifiers require to be encoded by the user, implicitly (using the auto mode and/or the legacy mode) and/or explicitly, the combination resulting in their effective encoding.

Implicit modifier encoding

  Virtual modifiers always compute their implicit encoding, which is defined for a given virtual modifier by the bitwise OR of all the real modifier maps where the virtual modifier is in the virtual modifier map of the corresponding key.

  Example:

  xkb_symbols {
  virtual_modifiers Alt;
  // Virtual modifier map: Alt is bound to <LALT>
  // Note: alternatively one can use xkb_compat interpretations.
  key <LALT> { virtualModifier = Alt };
  // Real modifier map: Mod1 is bound to <LALT>
  modifier_map Mod1 { <LALT> };
  // Implicit encoding: Alt = Mod1
  };
Explicit modifier encoding

  Virtual modifiers can optionally define an initial mapping using the virtual_modifiers statements:

  virtual_modifiers M1 = Mod1; // Single real modifier
  virtual_modifiers M2 = Mod4+Mod5;// Real modifier mask
  virtual_modifiers M3 = 0x400; // Numeric mask

  See Modifiers declarations for further information.

  Warning
    Although it is explicit, this may not be the effective encoding, detailed hereinafter.
Effective modifier encoding

  The effective encoding is the bitwise OR of the explicit modifier encoding and the implicit modifier encoding.

  Note
    If using XKB_KEYMAP_FORMAT_TEXT_V2, virtual modifiers that were not mapped either implicitly using the virtualModifier/modifier_map feature hereinabove or explicitly, then they are mapped to their canonical mapping.

  Example:

  xkb_symbols {
  virtual_modifiers Alt, Meta, Super = none, Hyper = 0x1000, Useless = none;
  // Virtual modifier maps
  // Note: alternatively one can use xkb_compat interpretations.
  key <LALT> { virtualModifier = Alt }; // Alt is bound to <LALT>
  key <LWIN> { virtualModifier = Super }; // Super is bound to <LWIN>
  key <RWIN> { virtualModifier = Super }; // Super is bound to <RWIN>
  key <HYPR> { virtualModifier = Hyper }; // Hyper is bound to <HYPR>
  // Real modifier maps
  modifier_map Mod1 { <LALT> }; // Mod1 is bound to <LALT>
  modifier_map Mod4 { <LWIN> }; // Mod4 is bound to <LWIN>
  modifier_map Mod5 { <RWIN> }; // Mod5 is bound to <RWIN>
  modifier_map Mod3 { <HYPR> }; // Mod3 is bound to <HYPR>
  };

  Modifiers encoding of the previous example
  Modifier | Index | Encoding
  --- | --- | ---
  |  | Canonical | Explicit | Implicit | Effective
  | (xkbcommon) |  | XKB_KEYMAP_FORMAT_TEXT_V1 | XKB_KEYMAP_FORMAT_TEXT_V2
  Alt | 8 | 0x100 |  | Mod1 | Mod1 | Mod1
  Meta | 9 | 0x200 |  |  | 0 (unmapped) | 0x200 (canonical, xkbcommon value)
  Super | 10 | 0x400 | 0 | Mod4 + Mod5 | Mod4 + Mod5 | Mod4 + Mod5
  Hyper | 11 | 0x800 | 0x1000 |  | 0x1000 | 0x1000
  Useless | 12 | 0x1000 | 0 |  | 0 (unmapped) | 0 (explicit mapping)

## Canonical and non-canonical modifiers

A canonical modifier have an encoding defined by: 1 << mod_index, where mod_index is:

- Fixed for the real modifiers, in order to match the X11 values. See real modifiers mapping.
- Implementation-dependent for the the virtual modifiers. See xkbcomp and libxkbcommon implementations for further details.

## Usual modifiers and associated keysyms

The following table summarizes the modifiers defined in xkeyboard-config 2.44:

Modifier | Type | Compat files | Associated keysyms
--- | --- | --- | ---
Shift | Real | compat/basic | Shift_L, Shift_R
compat/iso9995 | Shift_L, Shift_R, ISO_Level2_Latch
Lock | Real | compat/basic, | Caps_Lock
compat/caps
Control | Real | compat/basic | Control_L, Control_R
Alt | Virtual | compat/misc, | Alt_L, Alt_R
compat/pc
Meta | Virtual | compat/misc | Meta_L, Meta_R
Super | Virtual | compat/misc | Super_L, Super_R
Hyper | Virtual | compat/misc | Hyper_L, Hyper_R
ScrollLock | Virtual | compat/misc | Scroll_Lock
NumLock | Virtual | compat/basic, | Num_Lock,
compat/level5 | (ISO_Level5_Lock)
LevelThree | Virtual | compat/iso9995 | ISO_Level3_Shift, ISO_Level3_Latch, ISO_Level3_Lock
LevelFive | Virtual | compat/level5 | ISO_Level5_Shift, ISO_Level5_Latch, ISO_Level5_Lock
Kana_Lock | Virtual | compat/japan | Kana_Lock
Square | Virtual | compat/olpc | KP_Home
Cross | Virtual | compat/olpc | KP_Next
Circle | Virtual | compat/olpc | KP_End
Triangle | Virtual | compat/olpc | KP_Prior

## Modifiers portability

### Avoid using numeric modifier masks

Note
  Any field that accept virtual modifier names is a virtual modifier mask, denoting virtual modifiers indices. These indices are implementation-specific and should not be leaked. Therefore any numeric value used for these fields should be interpreted equally as a virtual modifier mask, and is thus implementation-specific.

Important
  In order to preserve modifier encoding portability, XKB implementations are recommended to avoid numeric modifier masks and to use virtual modifiers names whenever possible when serializing the keymap. This avoids leaking the indices of the modifiers.

### xkbcomp and libxkbcommon implementations

Attention
  This section is not part of the keymap text format specification and presents libxkbcommon’s implementation details that may change, solely for the purpose of informing other XKB implementation. Users should not rely on this!

Both X11 xkbcomp and libxkbcommon currently implement modifiers indices as follow:

1. Real modifiers have the following indices:

   Name | Index
   --- | ---
   Shift | 0
   Lock | 1
   Control | 2
   Mod1 | 3
   Mod2 | 4
   Mod3 | 5
   Mod4 | 6
   Mod5 | 7

2. Virtual modifiers names are assigned to virtual modifier indices following their order of appearance in a keymap component, if that name was not previously assigned.
3. Indices are assigned in ascending order, from 0.
4. If an index is already assigned to a different name, then the next free index is used.
5. The order of the relevant keymap components used for virtual mods assignment is:
   1. xkb_types
   2. xkb_compat
   3. xkb_symbols
6. A virtual modifier mask always denotes virtual modifiers indices.

Note
  It suffices to declare all virtual modifiers in xkb_types (or if empty, whatever non-empty section afterwards, in the order specified above) in their ascending indices order to use virtual modifiers indices compatible with libxkbcommon.

## Example: define and use a modifier, step by step

We will use the example of the real modifier Shift and the virtual modifier LevelThree in xkeyboard-config.

In order to define and use a modifier, one must:

1. Define its behavior and keysym binding in the `xkb_compat` section:

   // Declare virtual modifiers. Shift being real modifier,
   // we do not need to add it here.
   virtual_modifiers LevelThree;
   // Set defaults. They are overridden if set directly in the xkb_symbols.
   interpret.repeat= False; // only applied on first level
   setMods.clearLocks= True;
   latchMods.clearLocks= True;
   latchMods.latchToLock= True;
   // Default statement for real modifiers: any key bound to a real
   // modifier via modifier_map will set this modifier at all its
   // levels.
   // Here only to illustrate: do not add it!
   interpret Any + Any {
   action= SetMods(modifiers=modMapMods);
   };
   // Shift being real modifier, we do not need a corresponding
   // interpret statement because the previous one suffices.
   // Let’s associate LevelThree to the keysym ISO_Level3_Shift
   // First, match the keys and their levels with the
   // ISO_Level3_Shift keysym and with any real modifier
   // (Any = AnyOf(all)) in its modmap.
   interpret ISO_Level3_Shift+Any {
   // Only match the first level of the first group
   useModMapMods= level1;
   // Add the virtual modifier to the key’s vmodmap
   virtualModifier= LevelThree;
   // Activate the LevelThree modifier (depressed mode)
   action= SetMods(modifiers=LevelThree);
   };
   // Then for keys and their levels with the
   // ISO_Level3_Shift keysym but with either no real modifier
   // in its modmap or a level higher than 1.
   // Indeed:
   // • In case the level is higher than 1 there is no match
   // in the previous statement.
   // • The condition is equivalent to
   // ISO_Level3_Shift+AnyOfOrNone(all), but since
   // the previous statement ISO_Level3_Shift+Any is more
   // specific, it will be matched before this one.
   interpret ISO_Level3_Shift {
   // Activate the LevelThree modifier (depressed mode)
   action= SetMods(modifiers=LevelThree);
   };

2. Define key types that use it in the `xkb_types` section:

   // Declare virtual modifiers. Shift being real modifier,
   // we do not need to add it here.
   virtual_modifiers LevelThree;
   type "FOUR_LEVEL" {
   // Key type modifier mask: all the modifiers used in the key type
   modifiers = Shift + LevelThree;
   map[None] = Level1;
   map[Shift] = Level2;
   map[LevelThree] = Level3;
   map[Shift+LevelThree] = Level4;
   level_name[Level1] = "Base";
   level_name[Level2] = "Shift";
   level_name[Level3] = "AltGr";
   level_name[Level4] = "Shift AltGr";
   };

3. Bind it to a keycode in the `xkb_symbols` section:

   1. Map keysyms used in the xkb_compat section hereinabove.
   2. Bind real modifiers to keys using these keysyms with modifier_map.

   Note: Only one key binding to real modifier is required. The corresponding keysym must then be on the first level of the first Group.

   Note: One can optionally bind directly a virtual modifier to a key using virtualmodifiers instead of doing it in the xkb_compat section. But the recommended way is to use the xkb_compat section.

   // Shift: defined in pc symbols
   key <LFSH> {[ Shift_L ]};
   key <RTSH> {[ Shift_R ]};
   modifier_map Shift { Shift_L, Shift_R };
   // The previous will resolve to:
   // modifier_map Shift { <LFSH>, <RTSH> };
   // Thus the real modifier Shift is added to the modmap of
   // <LFSH> and <RTSH>.
   // The “Any + Any” interpret statement matches <LFSH> and <RTSH>,
   // therefore these keys set the Shift modifier.
   // LevelThree: defined in pc symbols
   // With the following 2 lines:
   // 1. The modifier keysym is on the first level of the first group.
   // 2. The real modifier Mod5 is bound to <LVL3>,
   // i.e. Mod5 is added to its modmap.
   // 3. It matches the interpret statement “ISO_Level3_Shift+Any”,
   // which adds the LevelThree modifier to the vmodmap of <LVL3>.
   // 4. The mapping of LevelThree to real modifiers is the union
   // of modmaps with corresponding vmodmaps containing
   // LevelThree. In our case there is only one: therefore
   // LevelThree maps to Mod5.
   key <LVL3> {[ ISO_Level3_Shift ]};
   modifier_map Mod5 { <LVL3> };
   // LevelThree: defined in level3 symbols
   // Not bound to a real modifier, so interpret statement
   // “ISO_Level3_Shift” applies.
   key <RALT> {[ISO_Level3_Shift], type[group1]="ONE_LEVEL" };
   // Note: we could have the following line, but it is not necessary
   // because we have the mappings of <LVL3>.
   // modifier_map Mod5 { <RALT> };
   // Warning: if we had the for example the following line, the
   // mapping of LevelThree to real modifiers would be “Mod1+Mod5”.
   // modifier_map Mod1 { <RALT> };
   // Alternative definitions, without using interpret statements
   virtual_modifiers LevelThree;
   key <LVL3> { virtualmodifiers=LevelThree
   , repeats=False
   , symbols[Group1] = [ISO_Level3_Shift]
   , actions[Group1] = [SetMods(modifiers=LevelThree)] };
   modifier_map Mod5 { <LVL3> };
   key <RALT> { repeat=False
   , symbols[Group1] = [ISO_Level3_Shift]
   , actions[Group1] = [SetMods(modifiers=LevelThree)]
   , type[group1]="ONE_LEVEL" };
   // FOUR_LEVEL key type example from latin symbols
   key <AB05> {[b, B, leftdoublequotemark, leftsinglequotemark]};

# Key actions

The following table provide an overview of the available actions:

Category | Action name | Alias | Description
--- | --- | --- | ---
Ineffectual action | NoAction |  | Default action: implicitly do nothing
VoidAction |  | Explicitly do nothing
Modifier action | SetMods |  | Modifies the depressed modifiers
LatchMods |  | Modifies the latched modifiers
LockMods |  | Modifies the locked modifiers
Group action | SetGroup |  | Modifies the base group
LatchGroup |  | Modifies the latched group
LockGroup |  | Modifies the locked group
Legacy action | MovePointer | MovePtr | Move the mouse pointer
PointerButton | PtrBtn | Simulate a mouse button press
LockPointerButton | LockPtrBtn | Simulate a mouse button press, locked until the action’s key is pressed again.
SetPointerDefault | SetPtrDflt | Set the default select button (???)
SetControls |  | Set the standard XKB controls
LockControls |  | Lock the standard XKB controls
TerminateServer | Terminate | Shut down the X server
SwitchScreen |  | Switch virtual X screen
Private |  | Raw encoding of an action
Unsupported legacy action | RedirectKey | Redirect | Emulate pressing a key with a different key code
ISOLock |  | Convert ordinary modifier key actions into lock actions while this action is active
DeviceButton | DevBtn | Emulate an event from an arbitrary input device such as a joystick
LockDeviceButton | LockDevBtn | Emulate an event from an arbitrary input device such as a joystick
DeviceValuator | DevVal | TODO
MessageAction | Message | Generate an arbitrary special-purpose XKB event

Common syntax:

- Boolean values:
  - true, yes, on
  - false, no, off

## Ineffectual actions

NoAction

  Default action: implicitly do nothing. Does not override previous actions and is dropped.

  No parameters.

VoidAction

  Explicitly do nothing. Does override previous actions and is not dropped.

  No parameters.

  Note
    This is a libxkbcommon extension. In order to maintain backward-compatibility, it serializes to LockControls(controls=none,affect=neither).
  Since
    1.10.0

## Modifiers actions

There are 3 modifiers actions:

SetMods

  Modifies the depressed modifiers.

  Parameters
  Name | Aliases | Data type | Default value | Description
  --- | --- | --- | --- | ---
  modifiers | mods | Modifier mask | none (0) | The list of modifiers to modify, separated by +, or the special value modMapMods. The latter means the parameter value has to be read from the vmodmap attribute of the key.
  clearLocks |  | boolean | false | See its use hereinafter
  unlockOnPress |  | boolean | false | Control whether locked modifiers are unlocked on key press or release (default). See hereinafter for further details. Note Available since 1.11, only with XKB_KEYMAP_FORMAT_TEXT_V2.

LatchMods

  Modifies the latched modifiers

  Parameters
  Name | Aliases | Data type | Default value | Description
  --- | --- | --- | --- | ---
  modifiers | mods | Modifier mask | none (0) | see SetMods.
  clearLocks |  | boolean | false | See its use hereinafter
  latchToLock |  | boolean | false | See its use hereinafter
  latchOnPress |  | boolean | false | Control whether latched modifiers are latched on key press or release (default). See hereinafter for further details. Note Available since 1.11, only with XKB_KEYMAP_FORMAT_TEXT_V2.
  unlockOnPress |  | boolean | false | Control whether locked modifiers are unlocked on key press or release (default). See hereinafter for further details. Note It is implied if both latchOnPress=true and clearLocks=true. Available since 1.11, only with XKB_KEYMAP_FORMAT_TEXT_V2.

LockMods

  Modifies the locked modifiers.

  Parameters
  Name | Aliases | Data type | Default value | Description
  --- | --- | --- | --- | ---
  modifiers | mods | Modifier mask | none (0) | see SetMods
  affect |  | enumeration: lock unlock both neither | both | lock: the action only locks the modifier, but cannot unlock it. unlock: the action only unlocks modifier, but cannot lock it. both: the first key press locks the modifier and the second key press releases the modifier.. neither: do not lock nor unlock, i.e. do nothing.
  unlockOnPress |  | boolean | false | Control whether locked modifiers are unlocked on key press or release. See hereinafter for further details. Note Available since 1.11, only with XKB_KEYMAP_FORMAT_TEXT_V2.

Todo
  highlight that there is reference counting for the modifiers, e.g. to manage multiple physical keys for the same modifier.

These actions perform different tasks on key press and on key release:

Effects of modifiers actions
Action | On key press | On key release
--- | --- | ---
SetMods | If clearLocks and unlockOnPress are true, unlock the target modifiers. Adds modifiers to depressed modifiers that were not unlocked. | Removes modifiers added on press from depressed modifiers, provided that no other key which affects the same modifiers is logically down. If clearLocks is true, unlockOnPress is false and no other key were operated simultaneously with this key, then the modifiers will be removed as well from the locked modifiers.
LatchMods | If unLockOnPress and clearLocks are true and target modifiers were locked, then unlocks them and clear the action. Otherwise if latchOnPress is true, then adds modifiers to the latched modifiers. Otherwise adds modifiers to depressed modifiers. | If latchOnPress is false, then: Removes modifiers from depressed modifiers. If no keys were operated simultaneously with the latching modifier key: If clearLocks is true and unLockOnPress is false and target modifiers were locked, then unlock then stop here and clear the action. Otherwise add modifiers to latched modifiers. If latchToLock is true and if the target modifiers are latched, then unlatch them and lock them. Latch target modifiers that were not used by clearLocks and latchToLock. Otherwise unlatch the target modifiers and clear the action.
LockMods | If unlockOnPress is true and some of the target modifiers were locked before the key press, then unlock them if noUnlock false. Otherwise: add target modifiers to depressed modifiers; if noLock is false, add target modifiers to the locked modifiers. | If unlockOnPress is true and triggered unlocking on key press, do nothing. Otherwise: remove modifiers from the depressed modifiers, if no other key that affect the same modifiers is down; if noUnlock is false and if any target modifiers was locked before the key press, unlock them.

## Group actions

There are 3 group actions:

SetGroup

  Modifies the base group.

  Parameters
  Name | Data type | Default value | Description
  --- | --- | --- | ---
  group | Group index: 1-based numbering either absolute (no sign) or relative (+/- sign) | 0 | Target group or group delta
  clearLocks | boolean | false | See its use hereinafter

LatchGroup

  Modifies the latched group.

  Parameters
  Name | Data type | Default value | Description
  --- | --- | --- | ---
  group | Group index (see SetGroup) | 0 | Target group or group delta
  clearLocks | boolean | false | See its use hereinafter
  latchToLock | boolean | false | See its use hereinafter

LockGroup

  Modifies the locked group.

  Parameters
  Name | Data type | Default value | Description
  --- | --- | --- | ---
  group | Group index (see SetGroup) | 0 | Target group or group delta
  lockOnRelease | boolean | false | Control whether to trigger the group change on key press (default) or release. See further details hereinafter Note Available since 1.11, only with XKB_KEYMAP_FORMAT_TEXT_V2.

Effects of group actions
Action | On key press | On key release
--- | --- | ---
SetGroup | If the group parameter is absolute, key press events sets the base keyboard group to group. Otherwise, it adds group to the base keyboard group. In either case, the resulting effective keyboard group is brought back into range depending on the value of the GroupsWrap control for the keyboard. | If no keys were operated simultaneously with this key and the clearLocks parameter is set, key release also sets the locked keyboard group to Group1.
LatchGroup | Same as SetGroup. | Same as SetGroup. If no keys were operated simultaneously with the latching group key and the clearLocks parameter was not set or had no effect, key release has the following additional effects: If latchToLock parameter is set and the latched keyboard group is not the first group, the key release adds the delta applied by the corresponding key press to the locked keyboard group and subtracts it from the latched keyboard group. The locked and effective keyboard group are brought back into range according to the value of the global GroupsWrap control for the keyboard. Otherwise, key release adds the key press delta to the latched keyboard group.
LockGroup | If lockOnRelease is set, then key press has no effect. Otherwise: if the group is absolute, key press sets the locked keyboard group to group; otherwise, key press adds group to the locked keyboard group. In either case, the resulting locked and effective group is brought back into range depending on the value of the GroupsWrap control for the keyboard. | If lockOnRelease is not set, then key release has no effect. Otherwise, if any other key was pressed after the locking key, then key release has no effect. This enables e.g. using Alt+Shift combination in any order. Shift down, Alt down, Alt up, Shift up Shift down, Alt down, Shift up, Alt up Alt down, Shift down, Shift up, Alt up Alt down, Shift down, Alt up, Shift up This would not be possible if locking was cancelled by key release too. Otherwise, it has the same effect than a key press without lockOnRelease set.

## Legacy X11 actions

Attention
  The following legacy actions are kept for compatibility only: they are parsed and validated but have no effect. This allows to use keymaps defined in `xkeyboard-config` for both X11 and Wayland.

### Pointer actions

MovePointer
MovePtr

  Move the mouse pointer

  Todo
    MovePointer parameters

PointerButton
PtrBtn

  Simulate a mouse button press

  Todo
    PointerButton parameters

LockPointerButton
LockPointerBtn
LockPtrButton
LockPtrBtn

  Simulate a mouse button press, locked until this actiion’s key is pressed again

  Todo
    LockPointerButton parameters

SetPointerDefault
SetPtrDflt

  Set the default select button (???)

  Todo
    SetPointerDefault parameters

### Control flags actions

SetControls

  Set the standard XKB controls

  Parameters
  Name | Alias | Data type | Default value | Description
  --- | --- | --- | --- | ---
  controls | ctrls | Mask of the following enumeration: RepeatKeys Repeat AutoRepeat SlowKeys BounceKeys StickyKeys MouseKeys MouseKeysAccel AccessXKeys AccessXTimeout AccessXFeedback AudibleBell IgnoreGroupLock Overlay1 Overlay2 Plus 2 special values: all none | 0 | Standard XKB controls

LockControls

  Lock the standard XKB controls

  Parameters
  Name | Alias | Data type | Default value | Description
  --- | --- | --- | --- | ---
  controls | ctrls | Mask (see SetControls) | 0 | Standard XKB controls
  affect |  | enumeration: lock unlock both neither | both | TODO

### Server actions

TerminateServer

  Shut down the X server

  No parameters.

SwitchScreen

  Todo
    SwitchScreen

### Private action

Raw encoding of an action. Aimed to support arbitrary action unknown to the XKB compiler.

Warning
  This assumes that the corresponding action’s C struct is laid out in memory exactly as described in the XKB specification and libraries. However, libxkbcommon have changed these structs in various ways, so this assumption is no longer true and the actions defined in the XKB protocol are unsupported.

Parameters
Name | Data type | Default value | Description
--- | --- | --- | ---
type | integer | 0 | Action type, as encoded in the XKB protocol
data | byte array or a string of exactly 7 bytes | "0000000" | Raw byte encoding of the action following the XKB protocol

Examples:

- Private(type=123, data="abcdefg");
- Private(type=123, data[1]=0, data[2]=100, data[3]=12);

## Unsupported legacy X11 actions

Attention
  The following legacy actions are unsupported: they are parsed and but not validated and are then completely ignored.

### Redirect key

RedirectKey emulates pressing a key with a different key code.

RedirectKey normally redirects to another key on the same device as the key or button which caused the event, else on the core keyboard device.

Parameters
Name | Aliases | Data type | Default value | Description
--- | --- | --- | --- | ---
key | keycode, kc | keycode | 0 | Target keycode to emulate
clearmodifiers | clearmods | modifier mask | none (0) | Modifiers to clear
modifiers | mods | modifier mask | none (0) | Modifiers to add

Effects
On key press | On key release
--- | ---
Key press causes a key press event for the key specified by the key parameter instead of for the actual key. The state reported in this event reports of the current effective modifiers changed as follow: Modifiers in the clearmodifiers parameter are cleared. Modifiers in the modifiers parameter are set. | Key release causes a key release event for the key specified by the key parameter; the state field for this event consists of the effective modifiers at the time of the release, changed as described on the key press.

### ISO lock

Todo
  ISOLock

### Device actions

DeviceButton

  Todo
    DeviceButton

LockDeviceButton

  Todo
    LockDeviceButton

DeviceValuator

  Todo
    DeviceValuator

### Message

Todo
  ActionMessage

# The “xkb_geometry” section

This section aims to describe the physical layout of a keyboard and its main use case is to produce a picture of the keyboard via e.g. the xkbprint program.

Warning
  libxkbcommon does not support this section: while it can parse the syntax, it does not interpret it; the section is simply dropped so there is no API to query it and the keymap serialization does not contain it.

See also
  Compatibility with X11.