This is an ART area review of https://www.ietf.org/archive/id/draft-ietf-dispatch-mime-protobuf-03.html


## Issues:

### Section 4. Encoding Considerations

> For binary forms that need to transit non-binary transports, a base64 Content-Transfer-Encoding (xref to [RFC4648]) is recommended.

I worry that this statement might lead people to think they should use this as a header in HTTP, when RFC7231 says it should not be https://www.rfc-editor.org/rfc/rfc7231#appendix-A.5.  

Perhaps simply saying the following would be safer:

> For binary forms that need to transit non-binary transports, a base64 encoding (xref to [RFC4648]) is recommended.


### 7.1. Registration 

> Protobuf implementations should accept all versions of wire encodings defined at the time of implementation.

Is it appropriate to state this requirement in a media type registration? Should this not be content of the protobuf specification instead?

## Nits:

### 6. Security Considerations

> While it is common for a protobuf definition to be used as input to a code generator which then produces something executable, but that applies to the schema language, not serializations.

There is something grammatically off with the "While ..., but" part of this sentence. I think the "but" can be removed.


In general this doc looks good to me.

Darrel