For someone not steeped in IPv6 lore, reading this draft feels like arriving during Act Three of a five-act opera. The plot so far, I believe, is that IPv6 allows long chains of extension headers which can cause processing problems that have led some routers to disallow them altogether. Also, large headers in fixed size fast path memory can keep routers from seeing application and port numbers that some rules use. Hence this document proposes limits on header size and ordering that we hope everyone can live with.

The motivation is clear enough, the limits are explained in an understandable way, and as far as I can tell they are all reasonable.

I understand that the proposed status of this draft was recently changed from BCP to Informational on the sensible basis that there isn't enough practice yet to know what is best. Nonetheless it still contains RFC 2119 requirements language, which seems overly prescriptive for a document that describes what is so far a best guess. I think that all the upper case words can be turned into lower case and still make sense, while not offering a premature promise that if you do what they say, everyone will accept your traffic. We hope they do, but that will presumably be revealed in Act Four.