CDA FAQ

Links

• See CDA FAQ on the hl7.org website for a high level FAQ.
• See [1] for quick start guides related to CDA.

What sylesheet should be used to render a CDA document?=

See: Stylesheet Semantics.

Why is a document an Act ?

See: Why is a document an Act.

What schema version should be used for CDA R2

Can I use schema from the latest ballot? See: Document Versioning.

What sections are contained in a document?

The CDA R2 (as a generic architecture) doesn't mandate the use of particular sections in a document, nor does it mandate the use of LOINC as a coding system for sections. (Section.code is CWE <= DocumentSectionType. This vocabulary doesn't have a predefined value set.)

If your implementation has to conform to a particular CDA implementation guide (one defined by another organization, e.g. the US-realm CCD guide), then that implementation guide could (and probably will) mandate the use of LOINC section codes, as well as a predefined hierarchy of allowable sections in a CDA instance.

If you're in the process of creating your own implementation guide for a specific clinical document type, then you could decide to use LOINC (it has plenty of section codes), and you can define your own section hierarchy.

CDA R2 using a non-XML ITS

• In how far is CDA R2 "abstract"? - In other words: if one were to attempt to apply a different ITS (assuming there was one, e.g. ASN.1 or CORBA), what would the "open issues list" look like?

(CDA R2 Documentation) "Specific enhancements to the CDA Schema, above and beyond those defined in the HL7 V3 XML ITS, are described [..] in CDA XML Implementation (§ 6 )." Section 6 states: "The CDA Narrative Block, which is the XML content model of section.text, is manually crafted, as described above (see Section Narrative Block (§ 4.3.5 ))."

(Charlie McCay) The way that references between parts of the narrative block and the structured content are done in an XML specific way (reasonably enough because HL7 itself -as an standard- does not have an IIref mechanism agreed yet). This is the rationale for the schema edit: Add "ID" attribute, of type XML ID, to Section, ObservationMedia, RegionOfInterest

If one were to create a different ITS then the current CDA R2 XML schema or the manual tweaks made to them don't actually matter that much, as long as the tweaks didn't introduce new abstract concepts or constraints. One would start from the HMD (or in future: the MIF), additional work would be required (from an abstract point of view) in addition to the HMD to make it work:

1. add the constraints as defined for Narrative Text (in an abstract fashion - strucDoc will hopefully create one at some point in time)
2. deal with the IIRef issue in some way