Sign languages in the context of "Language isolate"

Phonology (formerly also phonemics or phonematics) is the branch of linguistics that studies how languages systematically organize their phonemes or, for sign languages, their constituent parts of signs. The term can also refer specifically to the sound or sign system of a particular language variety. At one time, the study of phonology related only to the study of the systems of phonemes in spoken languages, but now it may relate to any linguistic analysis either:

Sign languages have a phonological system equivalent to the system of sounds in spoken languages. The building blocks of signs are specifications for movement, location, and handshape. At first, a separate terminology was used for the study of sign phonology ("chereme" instead of "phoneme", etc.), but the concepts are now considered to apply universally to all human languages.

Indonesia is home to over 700 living languages spoken across its extensive archipelago. This significant linguistic variety constitutes approximately 10% of the world’s total languages, positioning Indonesia as the second most linguistically diverse nation globally, following Papua New Guinea. The majority of these languages belong to the Austronesian language family, prevalent in the western and central regions of Indonesia, including languages such as Acehnese, Sundanese, and Buginese. In contrast, the eastern regions, particularly Papua and the Maluku Islands, are home to over 270 Papuan languages, which are distinct from the Austronesian family and represent a unique linguistic heritage. The language most widely spoken as a native language is Javanese, primarily by the Javanese people in the central and eastern parts of Java Island, as well as across many other islands due to migration.

Languages in Indonesia are classified into nine categories: national language, locally used indigenous languages, regional lingua francas, foreign and additional languages, heritage languages, languages in the religious domain, English as a lingua franca, and sign languages.

British, Australian and New Zealand Sign Language (BANZSL, /ˈbænzəl/), or the British Sign Language (BSL) family, is a language family or grouping encompassing three related sign languages: British Sign Language, Auslan and New Zealand Sign Language (NZSL). The term BANZSL was coined informally by the linguists Trevor Johnston and Adam Schembri in the early 2000s. However, in 2024, Schembri remarked that the Wikipedia article on BANZSL had begun describing it with the more specific or authoritative meaning of "the language from which modern BSL and Auslan and New Zealand sign language have descended", a meaning that "took on a life of its own—something that we didn't intend". As a result, Schembri says he and Johnston have disowned the term due to pushback from Deaf communities, concerned that it is replacing the names of each of the three languages.

BSL, Auslan and NZSL all have their roots in a Deaf sign language used in Britain during the 19th century. The three languages in question are related in their use of similar grammar, manual alphabet, and high degree of lexical (sign) overlap.