HL7 data types define the kind of data that can be included in a field, and are used throughout the HL7 message structure. Examples would be a string, formatted text, timestamp, address, or coded element. Each data type may contain additional data types that are referenced as components or subcomponents. Complex data types use other data types to define the kind of data they can contain.
Certain data types cannot reference each other due to the nature of the components. For instance, a data type cannot reference data types that already reference multiple components, because there is no way to code the information at that level.
Extended composite name and ID number for organizations
Extended telecommunications number
Query selection criteria
Query input parameter list
Row column definition
Driver’s license number
Medical Records/Info Mgmt
Performing person time stamp
Scheduling class value pair
Understanding components and subcomponents
A data type may reference one or more additional data types as components or subcomponents. For example, the CK (composite ID with check digit) data type can be broken down into four components, each referencing a specific data type. One of these components (HD) also references three other data types as subcomponents.