Overview
ISO/IEC 9995-11:2015 specifies the functionality of dead keys and the repertoires of characters entered by dead keys within the ISO/IEC 9995 keyboard-layout framework. Primarily intended for word‑processing and text‑processing environments, the standard defines how dead keys interact with characters (including Unicode combining characters) and lists the expected results for common diacritical combinations.
Key topics and technical requirements
- Definition of a dead key: a key that produces a graphic character but does not advance the active position, so the character applies to the next input character.
- Relation to ISO/IEC 10646 (Unicode/UCS): dead-key behaviour is described with respect to combining characters as defined in ISO/IEC 10646; implementations must handle insertion and composition according to Unicode principles.
- Keyboard Functional Unit (KFU) buffering algorithm: the standard outlines steps for buffering combining characters, handling backspace, replacing buffered characters using lookup tables, using a “combining character application character”, and applying Unicode normalization form C for canonical composition before output.
- Combining-character + Space handling: dead key followed by space should produce a spacing clone of the combining character (or an alternative resulting character where specified). Table 1 lists MLS combining characters (e.g., U+0300 combining grave accent) and recommended spacing clones or alternatives.
- Peculiar characters (precomposed results): Table 2 enumerates characters that should result from specific dead-key + character sequences (e.g., combinations that yield double diacritics or symbols). Keyboard layouts may extend these lists for additional combinations.
- Conformance rule: a keyboard layout conforms if it contains dead keys and each dead key behaves as described in Clause 5; table entries need only be implemented for dead keys present.
Practical applications
- Keyboard and input-method designers: to define consistent dead‑key behavior across groups and levels.
- Operating system and driver developers: to implement KFU buffering, backspace rules, and Unicode composition semantics.
- Software vendors (word processors, text editors, localization tools): to ensure text input produces expected diacritics and precomposed characters.
- Localization and accessibility teams: to create layouts for multilingual or multiscript input that conform to international expectations.
Who uses this standard
- Hardware manufacturers (keyboards and firmware)
- OS vendors and input-method developers
- Standards bodies and localization engineers
- Software developers focused on international text input and typography
Related standards
- ISO/IEC 9995‑1 - General principles governing keyboard layouts
- ISO/IEC 10646 - Universal Coded Character Set (UCS) / Unicode-related combining character definitions
Keywords: ISO/IEC 9995-11:2015, dead keys, combining characters, keyboard layouts, Unicode, ISO/IEC 10646, diacritical marks, keyboard functional unit, normalization form C.
Open preview (PDF)Information technology — Keyboard layouts for office systems — Part 11: Functionality of dead keys and repertoires of characters entered by dead keys