Overview
ISO/IEC 14755:1997 specifies standardized input methods to enter characters from the repertoire of ISO/IEC 10646 (UCS) using a keyboard or other input device. The standard defines code‑independent techniques for selecting single‑ and multi‑octet characters by reference to their UCS catalog numbers (hexadecimal canonical form) and complements national keyboard layouts and language‑specific input methods rather than replacing them.
Key topics and requirements
- Four entry methods (defined in the standard):
- Basic (catalog) method - enter a character by typing its UCS catalog number (hexadecimal canonical or abbreviated form) between a beginning and an ending sequence.
- Keyboard‑symbol (meta) method - generate UCS characters associated with ISO/IEC 9995‑7 function symbols by pressing the corresponding function key after the beginning sequence.
- Screen‑selection method - select a displayed character on‑screen for data entry.
- Feedback method - identify characters shown on screen precisely for subsequent entry.
- Notation and identifiers
- UCS characters are referred to as Uxxxxxxxx (hexadecimal) or by their in text.
- Definitions include canonical form, catalog number, beginning/ending sequence, level, and Level 2 Select.
- Prerequisites
- Keyboard must provide an alphanumeric section with a space bar, digits 0–9 and the first six letters of the alphabet (for hexadecimal digits A–F).
- System must support the required key sequences and logical key states (not applicable to mechanical typewriters).
- Behavioral requirements
- Systems should accept abbreviated hexadecimal input (leading zeros may be omitted).
- If the selected UCS character is unavailable, the system should signal an error (e.g., audible beep).
Applications and users
ISO/IEC 14755 is aimed at implementers and stakeholders working on internationalized text input and character processing:
- Operating system and input method developers - to implement code‑independent character entry for large repertoires.
- Application developers (word processors, editors, IDEs) - to provide standard ways to input rare or non‑Latin characters.
- Keyboard and firmware designers - to support logical key states and Level 2 Select behaviors.
- Internationalization/localization engineers - to ensure consistent entry methods across scripts and encodings.
- Accessibility specialists - to provide predictable, standard character entry mechanisms for assistive technologies.
Related standards
- ISO/IEC 10646 (UCS) - universal character repertoire referenced throughout.
- ISO/IEC 9995 (Parts 1, 3, 7) - keyboard layout principles and symbols.
- ISO/IEC 646, 6937, 8859‑1 - examples of coded character sets and mappings used in implementations.
Keywords: ISO/IEC 14755:1997, input methods, ISO/IEC 10646, UCS, keyboard input, character entry, code‑independent, hexadecimal catalog number.
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