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The Unicode Consortium has a number of stability policies regarding the various standards, registries, and repositories that it develops or maintains. These policies are put in place to assure the continued reliability of these resources and to provide implementers guarantees about the limits of allowed kinds of changes for any updates and new versions. The Consortium may add further policies as appropriate in the future. The Technical Committees also have established Procedures that govern the workings of those committees.
Unlike many other standards, the Unicode Standard regularly requires updating to expand its repertoire of characters. New characters are added to meet a variety of uses, ranging from technical symbols to letters for regional scripts or for archaic languages. Character properties are also expanded or revised to meet new implementation requirements. However, changes to the standard must be constrained by the requirements of backward compatibility between versions. To that end, the Unicode Character Encoding Stability Policies limit the ways in which the Unicode Standard and related Unicode specifications can change. The Unicode Technical Committee is responsible for the technical adherence of its standards and specifications to this policy.
The Unicode Technical Standard #10, Unicode Collation Algorithm, is regularly updated to keeps its definitions and tables in synch with the Unicode Standard. The Unicode Collation Stability Policy limits the ways that algorithm and its associated data tables can change. The Unicode Technical Committee is responsible for the technical adherence of that standard to this policy.
The Unicode Consortium is the registration authority for the ISO 15924 standard for script codes. Changes to the set of registered codes must be constrained by the requirements of backward compatibility. To that end, the Unicode Registered Code Stability Policy limits the ways in which the registrar administers the registry.
The Unicode Locales Project develops and maintains the Unicode LDML standard and the associated data repository, the Unicode Common Locales Data Repository (CLDR). Changes to the standard and repository are constrained to ensure backward compatibility. The Unicode Locales Stability Policy spells out those constraints. The Unicode CLDR-TC is responsible for the technical adherence of its standard and repository to this policy.
