in section 1, you start to talk about HL7 v2 and CDA support for tagging... which is good background. These likely should be in a sub header, as the IG is about FHIR. and as such the IG should express clearly that FHIR from the START has had tagging as part of the model. This can be expressed as "because of the history with v2 and cda".  As currently stated it would seem that by the time the reader is done with section 1, they think that FHIR needs to now be retrofitted.