| id | No | string | Unique id for inter-element referencing |
| extension | No | Extension[] | Additional content defined by implementations |
| type | Yes | code | documentation / justification / citation / predecessor / successor / derived-from / depends-on / composed-of |
| label | No | string | Short label |
| display | No | string | Brief description of the related artifact |
| citation | No | markdown | Bibliographic citation for the artifact |
| url | No | url | Where the artifact can be accessed |
| document | No | Attachment | What document is being referenced |
| resource | No | canonical | What resource is being referenced |
