> ## 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.

# Annotation

> Base StructureDefinition for Annotation Type: A  text note which also  contains information about who made the statement and when.

## 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 |
| author\[x] | No       | Reference\<[Practitioner](/medical-api/fhir/resources/practitioner) / [Patient](/medical-api/fhir/resources/patient) / [RelatedPerson](/medical-api/fhir/resources/relatedperson) / [Organization](/medical-api/fhir/resources/organization)>, string | Individual responsible for the annotation     |
| time       | No       | dateTime                                                                                                                                                                                                                                              | When the annotation was made                  |
| text       | Yes      | markdown                                                                                                                                                                                                                                              | The annotation - text content (as markdown)   |