| Name | Flags | Card. | Type | Description & Constraints |
|---|---|---|---|---|
  Element | «A»N | Base | Base for all elements + Rule: All FHIR elements must have a @value or children Elements defined in Ancestors: | |
  id | C | 0..1 | string | Unique id for inter-element referencing |
  extension | 0..* | Extension | Additional content defined by implementations | |
| Documentation for this format | ||||