3GPP 21.900 v20.0.0 — the document's own text
4.10.3.1 Corrections to Releases
Taught in 3. What a Release is, and what freezing one costs (How standards actually get made, in depth), 4. The change request and the release (How standards actually get made, overview), 3. One idea, from proposal to published text (How standards actually get made, quick start).
Each release should be consistent and implementable to ensure interworking. This implies that essential corrections become normative parts of the Release as soon as possible. If essential changes to "old" functionality are made to a new release, similar corresponding changes shall be made to correct the same error in the specifications pertaining to all previous, non-closed, Releases. This is illustrated in figure A.