Frequently Asked Question

A data item is the actual record of a variable. This record can take two forms:

• That of a real value taken by the variable directly encoded in the record. This value can take different formats: binary (yes/no), numeric (65 for a heart rate), textual (e.g. Country = "Belgium", a concept with its code system (e.g. SNOMED CT identifier for a disease concept, LOINC code for an analysis carried out).

• A "reference". A reference is a link pointing to an external record. The element or value of the record is therefore not directly available in the file, but the file contains a pointer that can be followed to another information component to retrieve the complete information required. Example: in AllergyIntolerance, for the AllergyIntolerance.Reaction.Manifestation field, a "CodableReference" can be used from the FHIR R5 version, pointing to the Observation resource of the manifestation record that was made at the time the manifestation was present, by the emergency doctor, before the patient had seen the allergist, who created the record of the causal agent of the allergy after carrying out his or her tests.