> ## 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. # Communication > An occurrence of information being transmitted; e.g. an alert that was sent to a responsible provider, a public health agency that was notified about a reportable condition. ## Properties | Name | Required | Type | Description | | --------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------- | | identifier | No | [Identifier](/medical-api/fhir/data-types/identifier)\[] | Unique identifier | | instantiatesCanonical | No | canonical\[] | Instantiates FHIR protocol or definition | | instantiatesUri | No | uri\[] | Instantiates external protocol or definition | | basedOn | No | Reference\\[] | Request fulfilled by this communication | | partOf | No | Reference\\[] | Part of this action | | inResponseTo | No | Reference\<[Communication](/medical-api/fhir/resources/communication)>\[] | Reply to | | status | Yes | code | preparation / in-progress / not-done / on-hold / stopped / completed / entered-in-error / unknown | | statusReason | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Reason for current status | | category | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | Message category | | priority | No | code | routine / urgent / asap / stat | | medium | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | A channel of communication | | subject | No | Reference\<[Patient](/medical-api/fhir/resources/patient) / [Group](/medical-api/fhir/resources/group)> | Focus of message | | topic | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept) | Description of the purpose/content | | about | No | Reference\\[] | Resources that pertain to this communication | | encounter | No | Reference\<[Encounter](/medical-api/fhir/resources/encounter)> | Encounter created as part of | | sent | No | dateTime | When sent | | received | No | dateTime | When received | | recipient | No | Reference\<[Device](/medical-api/fhir/resources/device) / [Organization](/medical-api/fhir/resources/organization) / [Patient](/medical-api/fhir/resources/patient) / [Practitioner](/medical-api/fhir/resources/practitioner) / [PractitionerRole](/medical-api/fhir/resources/practitionerrole) / [RelatedPerson](/medical-api/fhir/resources/relatedperson) / [Group](/medical-api/fhir/resources/group) / [CareTeam](/medical-api/fhir/resources/careteam) / [HealthcareService](/medical-api/fhir/resources/healthcareservice)>\[] | Message recipient | | sender | No | Reference\<[Device](/medical-api/fhir/resources/device) / [Organization](/medical-api/fhir/resources/organization) / [Patient](/medical-api/fhir/resources/patient) / [Practitioner](/medical-api/fhir/resources/practitioner) / [PractitionerRole](/medical-api/fhir/resources/practitionerrole) / [RelatedPerson](/medical-api/fhir/resources/relatedperson) / [HealthcareService](/medical-api/fhir/resources/healthcareservice)> | Message sender | | reasonCode | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | Indication for message | | reasonReference | No | Reference\<[Condition](/medical-api/fhir/resources/condition) / [Observation](/medical-api/fhir/resources/observation) / [DiagnosticReport](/medical-api/fhir/resources/diagnosticreport) / [DocumentReference](/medical-api/fhir/resources/documentreference)>\[] | Why was communication done? | | payload | No | CommunicationPayload | Message payload | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - content\[x] | Yes | string, [Attachment](/medical-api/fhir/data-types/attachment), Reference\ | Message part content | | note | No | [Annotation](/medical-api/fhir/data-types/annotation)\[] | Comments made about the communication | ## Search Parameters | Name | Type | Description | Expression | | ---------------------- | --------- | ------------------------------------------------------------------------------------------------- | ----------------------------------- | | based-on | reference | Request fulfilled by this communication | Communication.basedOn | | category | token | Message category | Communication.category | | encounter | reference | Encounter created as part of | Communication.encounter | | identifier | token | Unique identifier | Communication.identifier | | instantiates-canonical | reference | Instantiates FHIR protocol or definition | Communication.instantiatesCanonical | | instantiates-uri | uri | Instantiates external protocol or definition | Communication.instantiatesUri | | medium | token | A channel of communication | Communication.medium | | part-of | reference | Part of this action | Communication.partOf | | patient | reference | Focus of message | Communication.subject | | received | date | When received | Communication.received | | recipient | reference | Message recipient | Communication.recipient | | sender | reference | Message sender | Communication.sender | | sent | date | When sent | Communication.sent | | status | token | preparation / in-progress / not-done / on-hold / stopped / completed / entered-in-error / unknown | Communication.status | | subject | reference | Focus of message | Communication.subject | ## Inherited Properties | Name | Required | Type | Description | | ----------------- | -------- | ------------------------------------------------------ | ------------------------------------------------------ | | id | No | string | Logical id of this artifact | | meta | No | [Meta](/medical-api/fhir/data-types/meta) | Metadata about the resource | | implicitRules | No | uri | A set of rules under which this content was created | | language | No | code | Language of the resource content | | text | No | [Narrative](/medical-api/fhir/data-types/narrative) | Text summary of the resource, for human interpretation | | contained | No | Resource\[] | Contained, inline Resources | | extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored | To view the FHIR specification for this resource, see [Communication](https://www.hl7.org/fhir/StructureDefinition/Communication).