wording i conformance clause should clarify the status of SHOULD normative statements

Each conformance clause sub-section starts with something that looks like a mandatory requirement:

e.g.:

"A network device MUST conform to the following normative statements:"

But many of the following statements are optional (SHOULD) in the specification body. So it is then confusing to say "... MUST conform to a SHOULD statement...."

That is why it is NOT recommended to use normative language like MUST (and even less SHOULD) in a conformance clause. A conf clause is not there to tell you what to do or not do (MUST....), but only to state under which conditions you can claim conformance to XYZ.

It is better to say:

"an implementation that satisfies all mandatory (MUST) requirements in 5.1.4.1, 5.1.6.2.... qualifies (or may claim conformance) as a VIRTIO1.1 network device"

Or in some conformance profiles, you can override a SHOULD in the spec body and make it mandatory.