The draft clearly focuses on the selected parts of the overall versioning topic. I appreciate it focuses on the clearly defined part of the problem and it is usable and useful even separately. It introduces ietf-yang-revisions@2021-11-04.yang and ietf-yang-library-revisions@2021-11-04.yang modules which seem clear and possible to implement to me. I didn't find any issue with the text of the draft or with the modules.