| # | | Name | Source | Ver | Description |
| 1 | | Alternate Canonical | hl7.fhir.uv.extensions.r4#1.0.0 | R4 | Used when the target of the reference has a type that is not allowed by the definition of the element. In general, this should only arise when wrangling between versions using cross-version extensions. |
| 2 | | Display Name | hl7.fhir.uv.extensions.r4#1.0.0 | R4 | The title or other name to display when referencing a resource by canonical URL. |
| 3 | | Rendered Value | hl7.fhir.uv.extensions.r4#1.0.0 | R4 | Provides a rendered version of the value intended for human display. For example, a sensitive identifier (e.g. social security number) partially obscured by asterisks; a drivers licence number with dashes inserted; a date formatted as MMM dd, yyyy; etc. |
| 4 | | Resource Type | hl7.fhir.uv.crmi#current | R4 | Specifies the type of resource the canonical references. |
| 5 | | Target element | hl7.fhir.uv.extensions.r4#1.0.0 | R4 | Indicates that the reference has a particular focus in the target resource, a particular element of interest, identified by it's element id. |
| 6 | | Target path | hl7.fhir.uv.extensions.r4#1.0.0 | R4 | Indicates that the reference has a particular focus in the target resource, a particular element of interest, identified by a FHIRPath statement. The FHIRPath expression is limited to a the [simple subset](fhirpath.html#simple) with the additional limitation that .resolve() that is not allowed. |