Clinical Document Architecture

The HL7 Clinical Document Architecture (CDA) is an XML-based markup standard intended to specify the encoding, structure and semantics of clinical documents for exchange.

CDA is based on the HL7 Reference Information Model (RIM) and the HL7 Version 3 Data Types, although it can be used independently of any HL7 Version 3 messaging (i.e., CDA documents can be exchanged using other mechanisms, such as HL7 Version 2, DICOM, MIME attachments to email, http or ftp, etc.).

The CDA tries to ensure that the content will be human-readable and is therefore required to contain narrative text, yet still contain structure, and most importantly, allow for the use of codes (such as from SNOMED and LOINC) to represent concepts.

A good place to look for CDA information is in the Structured Documents Group of HL7, and the CDA FAQ