CLDR/LDML Keyboards

CLDR Keyboard Support in Keyman

SIL Keyman supports the CLDR/LDML Keyboard specification.

Introducing the CLDR/LDML Keyboard specification

LDML is the Locale Data Markup Language. It it an XML-based format specified as the Unicode Consortium’s specification UTS#35, maintained by the Common Locale Data Repository (CLDR) Technical Commitee. Part 7 of UTS#35 pertains to keyboard layouts. This specification has been updated as part of CLDR Release 46, authored by the CLDR Keyboard Subcommittee.

Like the Keyman Keyboard Language (.kmn) format, the LDML Keyboard format defines how keystrokes are interpreted and how keys are laid out in a virtual keyboard. The LDML format has been defined from the beginning to become a cross-platform industry standard, with active participation from several Unicode member organizations including SIL Global.

<!-- Example: French AZERTY Keyboard in LDML format -->
<layer modifier="shift">
  <row keys="1 2 3 4 5 6 7 8 9 0 degree plus" />
  <row keys="A Z E R T Y U I O P umlaut pound" />
  <row keys="Q S D F G H J K L M percent micro" />
  <row keys="close-angle W X C V B N question period slash section" />
  <row keys="space" />
</layer>

Keyman and LDML

As was announced in the March 2022 and February 2023 roadmaps, the Keyman team has been working in anticipation of LDML support in Keyman and Keyman Developer. Version 17.0 of Keyman includes support for LDML keyboards on desktop platforms - Windows, macOS, and Linux - and Keyman Developer 17.0 includes support for compiling and validation LDML keyboards.

As of February 2025:

• Support for LDML keyboards on the web and iOS and Android platforms is in development.

• A cross-platform visual design tool for LDML keyboards is in development.

The LDML support is being developed in our cross-platform Keyman Core component, which will enable a consistent feature set across all platforms including web by version 19.0, with a common code base.

Below is a screen capture showing the use of an LDML keyboard via a development version of Keyman for Linux.

Frequently Asked Questions for Keyman LDML Support

• How will the LDML format be supported with Keyman?

  From a technical perspective, the LDML format is a supported input to the Keyman Developer Compiler (kmc). The XML file is compiled into a KMX compiled keyboard file, and can be used just as .kmn files which are compiled to .kmx.

• How will the LDML format be supported with Keyman Developer?

  Keyman Developer 17.0 supports compiling LDML keyboards and basic XML editing. A full LDML editor is under development for Keyman Developer 19.0. (February 2025 update: This target slipped from 18.0 to 19.0.)

• What is the impact on existing developed keyboards in .kmn format?

  None. Keyman and Keyman Developer continue to support the thousands of languages in .kmn files and the .kmn format.

• Will there be a facility available to automatically convert .kmn to LDML or vice versa?

  The LDML specification is designed primarily to support new keyboard layouts. At a later stage, we would like to make available software to assist developers in migrating keyboards to the new format, including tooling to compare and verify the capabilities of a .kmn versus a similar LDML keyboard definition.

• I have other questions. Who should I ask?

  Please direct any other questions regarding LDML to the SIL Keyman Community.