Existing Wording
Note that the Diagnostic Order itself is not a request to perform the investigation - it is just a record of the fact that a request was made. To actually request that a diagnostic procedure be performed, additional workflow beyond simply the existence of a Diagnostic Order is required. This can be achieved by using an Order resource, with the Diagnostic Order referenced from the Order.details, or by using the Diagnostic Order resource in the context of an messaging or service workflow where the request is explicit or implicit.

Comments
It is confusing that Order is referenced as a very important Resource that is the actual request for the diagnostic service, yet Order is not listed in 4.0 among the clinical resources list. Rather, if you go down the "Clinical" resource list, you can only get to Order if you look at Diagnostic Order and happen to notice this sentence. Order should be elevated to be listed in 4.0 Clinical Resources.

I see that Order is listed in a different category, "Administrative – Scheduling/Ordering." That seems counterintuitive. Wouldn't nearly every clinician think of orders are belonging in their category?

Grahame's Comments
if it does, then everything does. Category is not that important. But this does show that clinical users - and lots of other users aside - just don't get the split between order and the domain order resources. This needs wider discussion

Disposition
Not Persuasive

Disposition Comment
Order is a workflow resource, not a clinical resource. It is used to manage fulfillment requests and other state transitions for the real "orders" (DiagnosticOrder, MedicationPrescription, etc.)