The goal of ISO/IEC 24757:2008 is to harmonize industry practices in matters of machine-readable keyboard descriptions (PCs, PDAs, various operating systems, etc.). It further aims to facilitate the production of interoperable drivers for the user and to better assist the user by offering a more precise mapping between the physical keyboard layout and geometrical configuration, and the logical interface available to the operating system and its applications.
ISO/IEC 24757:2008 provides a formal description format that can not only fully describe the international keyboards standards, but also the capabilities of keyboards on the current and future marketplace and their functioning with corresponding operating systems. It describes possible interactions between keys of a keyboard and standardizes the keyboard description so that it is machine-readable while staying relatively easy to interpret by human beings.
The keyboard description format is meant to be capable of describing existing capabilities of today's keyboard hardware and its associated software, plus foreseeable extensions. It relies on international standard format ISO SGML, in the form known as ISO RELAX NG, with an easy conversion to industry standard XML. Some additional functionality is covered, such as keyboards with programmable keys and keyboards with multiple key assignments such as telephone keypads.
The keyboard definition format is primarily intended to be used by the operating system, and during its boot process (e.g. in the BIOS), but can also be used for other purposes, such as reporting from the hardware of a keyboard to help the operating system configuring the keyboard driver, or to present the keyboard on screen with a user-friendly picture.
The keyboard definition format is described in four sections:
- a keyboard identification and general features section, including make and model, serial number, country or region and language to which the keyboard applies, engraving language identification, and distinctive features, such as relief, or presence of lights on keys.
- the hardware geometry layout, which indicates a largely known geometry layout, such as a 102-key PC keyboard. This section also gives physical information such as size of keys, and amount of pressure needed to activate keys.
- the keyboard layout, which gives the actual assignment of characters to each key.
- key combinations which gives combinations of keys, such as those of characters affected by dead keys.
A number of existing keyboard definition formats are described, together with a mapping between these description formats and the format defined in ISO/IEC 24757:2008.