The scope of the classification is all languages currently spoken in the world as defined above (see: Definition of language). In practice, only those languages that have significant numbers of speakers in Australia are separately identified in the classification structure. However, all languages currently spoken in the world are covered, notionally being included in the most appropriate category of the classification, even though they may not be listed in the coding index.
The issue of extinct or dead languages was not specifically addressed when developing the classification. If people speak extinct or dead languages for scholastic, religious or other purposes they are notionally included in the classification. If sufficient numbers of Australians speak an extinct or dead language, for whatever reason, it is separately identified in the classification, as is the case with Latin.
The classification also includes invented and sign languages as many statistical and administrative applications need to accommodate the whole range of responses to questions on languages used. 'Languages' which are not generally used as a means of communication between people, for example computer languages, are excluded from the classification.