3GPP 21.900 v20.0.0 — the document's own text
4.10.1.3 Specifications not propagated to next Release
Taught in 3. What a Release is, and what freezing one costs (How standards actually get made, in depth).
Specifications which are not propagated from Release N-1 to Release N in one of the above two methods shall be deemed not to form part of Release N. Under these circumstances, the responsible Group shall undertake a review of all other specifications of Release N to eliminate references to the specification concerned.