I am creating a DiagnosticOrder from the HL7 FHIR standard.
I would like to return the type of Order, such as "Full Blood Count" but also the category of this type, for example "Laboratory".
I see that DiagnosticOrder has an item.code property which can be a custom value. I presume this should probably be the Order type.
But how can I represent the category against this Order? Do I need to create an Extension or have I misunderstood the specification?