> ## Documentation Index
> Fetch the complete documentation index at: https://docs.metriport.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Reference

> Base StructureDefinition for Reference Type: A reference from one resource to another.

## Properties

| Name       | Required | Type                                                   | Description                                            |
| ---------- | -------- | ------------------------------------------------------ | ------------------------------------------------------ |
| id         | No       | string                                                 | Unique id for inter-element referencing                |
| extension  | No       | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations          |
| reference  | No       | string                                                 | Literal reference, Relative, internal or absolute URL  |
| type       | No       | uri                                                    | Type the reference refers to (e.g. "Patient")          |
| identifier | No       | [Identifier](/medical-api/fhir/data-types/identifier)  | Logical reference, when literal reference is not known |
| display    | No       | string                                                 | Text alternative for the resource                      |