3GPP 21.900 v20.0.0 — the document's own text

5.2 Choice of availability and distribution of stage 3 specification files

Taught in 4. The life of a 3GPP document, from blank page to published version (How standards actually get made, in depth).

For the availability and distribution of stage 3 specification files (e.g. OpenAPI specification, YANG, ASN.1, XSD, etc.) there are two optional alternatives, described in clauses 5B and 5C, and the principle of how the two alternatives are chosen is decided by the responsible Working Group. Clause 5C applies only for the choice when normative code parts of the stage 3 specification are normatively stored in the 3GPP Forge repository.