This document is clear and easy to understand.

From an IoT perspective, I don't have any specific concerns with it.  The CoAP spec (RFC 7522) was written referencing an early version of this I-D, so it has already been applied for designing IoT protocols.

There are a couple of small typos:
- In Section 4 part (1), there is a typo "an some" should just be one of those words.
- In Section 4 part (2), there is a typo "is is".