This draft is ready to go.  The recent revisions to the label count are adequately clear and the rest seems straightforward.

I wonder about the paragraph "A name server MUST ignore any non-empty ZONEVERSION payload data that might be present in the query message."  It's not wrong, but why call out this one particular error and not others like multiple ZONEVERSION options?  I'd take it out and leave the response to ill-formed queries undefined, or else be more general and say a server MUST ignore invalid ZONEVERSION options.