subalphabets

A subalphabet is a subset of the symbols from a larger writing system that a language or domain uses for its written form. In practice, a subalphabet may consist of the base letters of a parent script, augmented with diacritics or with letters that are treated as distinct units within a particular orthography.

Subalphabets arise when a language requires additional phonemes not represented by the core alphabet, or when orthographic conventions designate certain digraphs or accented forms as separate letters for purposes such as spelling, sorting, or traditional practice. Diacritics can create a broad range of added symbols within a single script, effectively expanding the usable alphabet without changing the underlying script type. In some languages, certain letters with diacritics are considered distinct from their unmarked counterparts for alphabetical ordering.

Examples include the Latin-based Turkish subalphabet, which uses letters such as ç, ğ, ı, İ, ö, ş, and ü; and the Spanish subalphabet, which includes ñ and accented vowels as integral letters in modern orthography. Vietnamese also employs a Latin-based subalphabet with extensive diacritics that mark tones and vowels, producing a large, phonemic repertoire within the Latin framework. In other domains, subalphabets appear in computing and encoding, where a program or font defines a subset of characters tailored to a locale or language, enabling efficient rendering and input.

Overall, subalphabets reflect how writing systems adapt to phonology, typography, and cultural conventions, while remaining part of a single cohesive script family. They influence sorting rules, input methods, and language standardization efforts.