The HD is designed to be more powerful and more general replacement for the application identifier of HL7 versions 2.1 and 2.2. It adds two additional components, the <universal ID> and the <universal ID type> to the former application ID (which is renamed more generically to be the namespace ID)
The basic definition of the HD is that it identifies an (administrative or system or application or other) entity that has responsibility for managing or assigning a defined set of instance identifiers (such as placer or filler number, patient identifiers, provider identifiers, etc.). This entity could be a particular health care application such as a registration system that assigns patient identifiers, a governmental entity such as a licensing authority that assigns professional identifiers or drivers' license numbers, or a facility where such identifiers are assigned.
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| Comp# | Comp TBL | FHIR | ||||||
|---|---|---|---|---|---|---|---|---|
| 1 | 342 | O | HD.1 | namespace ID | ||||
| 2 | 341 | O | - | - | HD.2 | universal ID | ||
| 3 | 343 | O | - | HD.3 | universal ID type |
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