There was some discussion of this on the CommonMark forums shortly after the initial release of CommonMark: https://talk.commonmark.org/t/commonmark-formal-gra

There was some discussion of this on the CommonMark forums shortly after the initial release of CommonMark: https://talk.commonmark.org/t/commonmark-formal-grammar/46 https://talk.commonmark.org/t/commonmark-formal-grammar/46 See in particular these comments by maradydd: https://talk.commonmark.org/t/commonmark-formal-grammar/46/17 https://talk.commonmark.org/t/commonmark-formal-grammar/46/1... https://talk.commonmark.org/t/commonmark-formal-grammar/46/22 https://talk.commonmark.org/t/commonmark-formal-grammar/46/2... https://talk.commonmark.org/t/commonmark-formal-grammar/46/23 https://talk.commonmark.org/t/commonmark-formal-grammar/46/2... I'm not sure they ever came to a conclusive answer (at least on this thread). Edit: Here is JGM himself saying he doesn't know: https://talk.commonmark.org/t/commonmark-formal-grammar/46/33 https://talk.commonmark.org/t/commonmark-formal-grammar/46/3...