may be subjective, particularly in the case of language varieties without established literary traditions, usage in education or media, or other factors that contribute to language conventionalization. Therefore, the standard should not be regarded as an authoritative statement of what distinct languages exist in the world (about which there may be substantial disagreement in some cases), but rather simply one useful way for identifying different language varieties precisely. Code space Since the code is three-letter alphabetic, one upper bound for the number of languages that can be represented is 26 × 26 × 26 = 17,576. Since ISO 639-2 defines special codes (4), a reserved range (520) and B-only codes (22), 546 codes cannot be used in part 3. Therefore, a stricter upper bound is 17,576 − 546 = 17,030. The upper bound gets even stricter if one subtracts the language collections defined in 639-2 and the ones yet to be defined in ISO 639-5. Macrolanguages There are 58 languages in ISO 639-2 which are considered, for the purposes of the standard, to be "macrolanguages" in ISO 639-3. Some of these macrolanguages had no individual language as defined by ISO 639–3 in the code set of ISO 639-2, e.g. 'ara' (Generic Arabic). Others like 'nor' (Norwegian) had their two individual parts ('nno' (Nynorsk), 'nob' (Bokmål)) already in ISO 639-2. That means some languages (e.g. 'arb', Standard Arabic) that were considered by ISO 639–2 to be dialects of one language ('ara') are now in ISO 639–3 in certain contexts considered to be individual languages themselves. This is an attempt to deal with varieties that may be linguistically distinct from each other, but are treated by their speakers as two forms of the same language, e.g. in cases of diglossia. For example: https://iso639-3.sil.org/code/ara (Generic Arabic, 639–2) https://iso639-3.sil.org/code/arb (Standard Arabic, 639–3) See for the complete list. Collective languages "A collective language code element is an identifier that represents a group of individual languages that are not deemed to be one language in any usage context." These codes do not precisely represent a particular language or macrolanguage. While ISO 639-2 includes three-letter identifiers for collective languages, these codes are excluded from ISO 639-3. Hence ISO 639-3 is not a superset of ISO 639-2. ISO 639-5 defines 3-letter collective codes for language families and groups, including the collective language codes from ISO 639-2. Special codes Four codes are set aside in ISO 639-2 and ISO