In my job I often have to deal with developers who were supposed to implement a standard and went with a "more like guidelines" mentality. So I'm with the autho

In my job I often have to deal with developers who were supposed to implement a standard and went with a "more like guidelines" mentality. So I'm with the author here: Either you claim to support protobuff and fully implement the spec as-is, or you cannot claim to support protobuf (with maybe some leeway on a "receive-only" label if you support a superset). Otherwise you have to name/specify your protocol modification.