ISO 24623-1:2018 describes the abstract metamodel designed to accommodate any corpus query language (QL) and providing a basis for coarse-grained classification. The metamodel consists of several components referred to as CQLF classes, levels, and modules, and is illustrated with examples from the Single-stream class (where a single data stream is used to organize the relevant data structures). Within this class, this document discusses three CQLF levels (Linear, Complex and Concurrent), as well as their subdivisions into modules, dictated by functional and modelling criteria.

ISO 24623-1:2018 does not provide a way to specify further details beyond the above-mentioned divisions, and neither does it contain within its scope QLs designed to query more than one concurrent data stream, as in multimodal corpora or in parallel corpora (such QLs can still be classified according to the criteria suggested here for less expressive QLs).