CS: Document Status
http://fhir.patientsknowbest.com/codesystem/document-status
https://www.hl7.org/fhir/STU3/codesystem.html
description
A [[Document]] in PKB has an associated status value.
concepts
concept[0]
code = READ
display = Read
definition = The document has been read by the patient.
concept[1]
code = UNREAD
display = Unread
definition = The document has not been read by the patient.