NHS Notify – FHIR Letter Printing Implementation Guide
0.1.0 - ci-build United Kingdom

NHS Notify – FHIR Letter Printing Implementation Guide - Local Development build (v0.1.0) built by the FHIR (HL7® FHIR® Standard) Build Tools. See the Directory of published versions

Resource Profile: LetterCommunicationRequest - Detailed Descriptions

Draft as of 2025-09-30

Definitions for the nhsnotify-letter-communicationrequest resource profile.

Guidance on how to interpret the contents of this table can be foundhere

0. CommunicationRequest
2. CommunicationRequest.status
Must Supporttrue
4. CommunicationRequest.category
BindingFor example codes, see https://nhsdigital.github.io/nhs-notify-standards/fhir/ValueSet/nhsnotify-letter-category
(example to https://nhsdigital.github.io/nhs-notify-standards/fhir/ValueSet/nhsnotify-letter-category)
Must Supporttrue
6. CommunicationRequest.subject
Control1..?
TypeReference(Patient)
Must Supporttrue
8. CommunicationRequest.subject.identifier
ShortNHS Number used to identify the patient
NoteThis is a business identifier, not a resource identifier (see discussion)
Must Supporttrue
10. CommunicationRequest.subject.identifier.system
Fixed Valuehttps://fhir.nhs.uk/Id/nhs-number
12. CommunicationRequest.payload
ShortAt least one letter payload (PDF metadata via DocumentReference)
Control1..?
Must Supporttrue
14. CommunicationRequest.payload.content[x]
[x] NoteSeeChoice of Data Typesfor further information about how to use [x]
SlicingThis element introduces a set of slices on CommunicationRequest.payload.content[x]. The slices areUnordered and Open, and can be differentiated using the following discriminators:
  • type @ $this
  • 16. CommunicationRequest.payload.content[x]:contentReference
    Slice NamecontentReference
    ShortDocumentReference wrapping the PDF binary
    Control1..1
    TypeReference(Letter PDF Document)
    [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
    Must Supporttrue
    18. CommunicationRequest.authoredOn
    ShortWhen the request was authored
    Must Supporttrue
    20. CommunicationRequest.requester
    ShortSubmitting system or responsible party
    Control1..?
    Must Supporttrue
    22. CommunicationRequest.recipient
    ShortIntended recipient entity (e.g. print fulfilment endpoint)
    Control1..?
    Must Supporttrue
    24. CommunicationRequest.sender
    ShortSource organization (ODS code)
    Must Supporttrue

    Guidance on how to interpret the contents of this table can be foundhere

    0. CommunicationRequest
    Definition

    A request to convey information; e.g. the CDS system proposes that an alert be sent to a responsible provider, the CDS system proposes that the public health agency be notified about a reportable condition.

    ShortA request for information to be sent to a receiver
    Control0..*
    Is Modifierfalse
    Summaryfalse
    Invariantsdom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources (contained.contained.empty())
    dom-3: If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource (contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty())
    dom-4: If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated (contained.meta.versionId.empty() and contained.meta.lastUpdated.empty())
    dom-5: If a resource is contained in another resource, it SHALL NOT have a security label (contained.meta.security.empty())
    dom-6: A resource should have narrative for robust management (text.`div`.exists())
    2. CommunicationRequest.implicitRules
    Definition

    A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

    ShortA set of rules under which this content was created
    Comments

    Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

    Control0..1
    Typeuri
    Is Modifiertrue because This element is labeled as a modifier because the implicit rules may provide additional knowledge about the resource that modifies it's meaning or interpretation
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    4. CommunicationRequest.modifierExtension
    Definition

    May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

    Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

    ShortExtensions that cannot be ignored
    Comments

    There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

    Control0..*
    TypeExtension
    Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the resource that contains them
    Summaryfalse
    Requirements

    Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

    Alternate Namesextensions, user content
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
    6. CommunicationRequest.status
    Definition

    The status of the proposal or order.

    Shortdraft | active | on-hold | revoked | completed | entered-in-error | unknown
    Control1..1
    BindingThe codes SHALL be taken from RequestStatushttp://hl7.org/fhir/ValueSet/request-status|4.0.1
    (required to http://hl7.org/fhir/ValueSet/request-status|4.0.1)

    The status of the communication request.

    Typecode
    Is Modifiertrue because This element is labelled as a modifier because it is a status element that contains status entered-in-error which means that the resource should not be treated as valid.
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    8. CommunicationRequest.category
    Definition

    The type of message to be sent such as alert, notification, reminder, instruction, etc.

    ShortMessage category
    Comments

    There may be multiple axes of categorization and one communication request may serve multiple purposes.

    Control0..*
    BindingFor example codes, see https://nhsdigital.github.io/nhs-notify-standards/fhir/ValueSet/nhsnotify-letter-categoryhttp://hl7.org/fhir/ValueSet/communication-category|4.0.1
    (example to https://nhsdigital.github.io/nhs-notify-standards/fhir/ValueSet/nhsnotify-letter-category)
    TypeCodeableConcept
    Is Modifierfalse
    Must Supporttrue
    Summaryfalse
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    10. CommunicationRequest.doNotPerform
    Definition

    If true indicates that the CommunicationRequest is asking for the specified action to not occur.

    ShortTrue if request is prohibiting action
    Comments

    The attributes provided with the request qualify what is not to be done.

    Control0..1
    Typeboolean
    Is Modifiertrue because If true this element negates the specified action. For Example, instead of a request for a communication, it is a request for the communication to not occur.
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Alternate Namesprohibited
    Meaning if MissingIf do not perform is not specified, the request is a positive request e.g. "do perform"
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    12. CommunicationRequest.subject
    Definition

    The patient or group that is the focus of this communication request.

    ShortFocus of message
    Control10..1
    TypeReference(Patient, Patient, Group)
    Is Modifierfalse
    Must Supporttrue
    Summaryfalse
    Alternate Namespatient
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    14. CommunicationRequest.subject.identifier
    Definition

    An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

    ShortNHS Number used to identify the patientLogical reference, when literal reference is not known
    Comments

    When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.

    When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference

    Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.

    Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

    NoteThis is a business identifier, not a resource identifier (see discussion)
    Control0..1
    TypeIdentifier
    Is Modifierfalse
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    16. CommunicationRequest.subject.identifier.use
    Definition

    The purpose of this identifier.

    Shortusual | official | temp | secondary | old (If known)
    Comments

    Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.

    Control0..1
    BindingThe codes SHALL be taken from IdentifierUsehttp://hl7.org/fhir/ValueSet/identifier-use|4.0.1
    (required to http://hl7.org/fhir/ValueSet/identifier-use|4.0.1)

    Identifies the purpose for this identifier, if known .

    Typecode
    Is Modifiertrue because This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one.
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Requirements

    Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.

    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    18. CommunicationRequest.subject.identifier.system
    Definition

    Establishes the namespace for the value - that is, a URL that describes a set values that are unique.

    ShortThe namespace for the identifier value
    Comments

    Identifier.system is always case sensitive.

    Control0..1
    Typeuri
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Requirements

    There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.

    Fixed Valuehttps://fhir.nhs.uk/Id/nhs-number
    ExampleGeneral: http://www.acme.com/identifiers/patient
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    20. CommunicationRequest.payload
    Definition

    Text, attachment(s), or resource(s) to be communicated to the recipient.

    ShortAt least one letter payload (PDF metadata via DocumentReference)Message payload
    Control10..*
    TypeBackboneElement
    Is Modifierfalse
    Must Supporttrue
    Summaryfalse
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    22. CommunicationRequest.payload.modifierExtension
    Definition

    May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

    Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

    ShortExtensions that cannot be ignored even if unrecognized
    Comments

    There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

    Control0..*
    TypeExtension
    Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the element that contains them
    Summarytrue
    Requirements

    Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

    Alternate Namesextensions, user content, modifiers
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
    24. CommunicationRequest.payload.content[x]
    Definition

    The communicated content (or for multi-part communications, one portion of the communication).

    ShortMessage part content
    Control1..1
    TypeReference(Resource), string, Attachment
    [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
    Is Modifierfalse
    Summaryfalse
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    SlicingThis element introduces a set of slices on CommunicationRequest.payload.content[x]. The slices areUnordered and Closed, and can be differentiated using the following discriminators:
    • type @ $this
    • 26. CommunicationRequest.payload.content[x]:contentReference
      Slice NamecontentReference
      Definition

      The communicated content (or for multi-part communications, one portion of the communication).

      ShortDocumentReference wrapping the PDF binaryMessage part content
      Control1..1
      TypeReference(Letter PDF Document, Resource), string, Attachment
      [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
      Is Modifierfalse
      Must Supporttrue
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      28. CommunicationRequest.authoredOn
      Definition

      For draft requests, indicates the date of initial creation. For requests with other statuses, indicates the date of activation.

      ShortWhen the request was authoredWhen request transitioned to being actionable
      Control0..1
      TypedateTime
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Must Supporttrue
      Summarytrue
      Alternate NamescreatedOn
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      30. CommunicationRequest.requester
      Definition

      The device, individual, or organization who initiated the request and has responsibility for its activation.

      ShortSubmitting system or responsible partyWho/what is requesting service
      Control10..1
      TypeReference(Practitioner, PractitionerRole, Organization, Patient, RelatedPerson, Device)
      Is Modifierfalse
      Must Supporttrue
      Must Support TypesNo must-support rules about the choice of types/profiles
      Summarytrue
      Alternate Namesauthor
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      32. CommunicationRequest.recipient
      Definition

      The entity (e.g. person, organization, clinical information system, device, group, or care team) which is the intended target of the communication.

      ShortIntended recipient entity (e.g. print fulfilment endpoint)Message recipient
      Control10..*
      TypeReference(Device, Organization, Patient, Practitioner, PractitionerRole, RelatedPerson, Group, CareTeam, HealthcareService)
      Is Modifierfalse
      Must Supporttrue
      Must Support TypesNo must-support rules about the choice of types/profiles
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      34. CommunicationRequest.sender
      Definition

      The entity (e.g. person, organization, clinical information system, or device) which is to be the source of the communication.

      ShortSource organization (ODS code)Message sender
      Control0..1
      TypeReference(Device, Organization, Patient, Practitioner, PractitionerRole, RelatedPerson, HealthcareService)
      Is Modifierfalse
      Must Supporttrue
      Must Support TypesNo must-support rules about the choice of types/profiles
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))

      Guidance on how to interpret the contents of this table can be foundhere

      0. CommunicationRequest
      Definition

      A request to convey information; e.g. the CDS system proposes that an alert be sent to a responsible provider, the CDS system proposes that the public health agency be notified about a reportable condition.

      ShortA request for information to be sent to a receiver
      Control0..*
      Is Modifierfalse
      Summaryfalse
      Invariantsdom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources (contained.contained.empty())
      dom-3: If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource (contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty())
      dom-4: If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated (contained.meta.versionId.empty() and contained.meta.lastUpdated.empty())
      dom-5: If a resource is contained in another resource, it SHALL NOT have a security label (contained.meta.security.empty())
      dom-6: A resource should have narrative for robust management (text.`div`.exists())
      2. CommunicationRequest.id
      Definition

      The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

      ShortLogical id of this artifact
      Comments

      The only time that a resource does not have an id is when it is being submitted to the server using a create operation.

      Control0..1
      Typeid
      Is Modifierfalse
      Summarytrue
      4. CommunicationRequest.meta
      Definition

      The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

      ShortMetadata about the resource
      Control0..1
      TypeMeta
      Is Modifierfalse
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      6. CommunicationRequest.implicitRules
      Definition

      A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

      ShortA set of rules under which this content was created
      Comments

      Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

      Control0..1
      Typeuri
      Is Modifiertrue because This element is labeled as a modifier because the implicit rules may provide additional knowledge about the resource that modifies it's meaning or interpretation
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      8. CommunicationRequest.language
      Definition

      The base language in which the resource is written.

      ShortLanguage of the resource content
      Comments

      Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

      Control0..1
      BindingThe codes SHOULD be taken from CommonLanguages
      (preferred to http://hl7.org/fhir/ValueSet/languages|4.0.1)

      A human language.

      Additional BindingsPurpose
      AllLanguagesMax Binding
      Typecode
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      10. CommunicationRequest.text
      Definition

      A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

      ShortText summary of the resource, for human interpretation
      Comments

      Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

      Control0..1
      TypeNarrative
      Is Modifierfalse
      Summaryfalse
      Alternate Namesnarrative, html, xhtml, display
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      12. CommunicationRequest.contained
      Definition

      These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope.

      ShortContained, inline Resources
      Comments

      This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags In their meta elements, but SHALL NOT have security labels.

      Control0..*
      TypeResource
      Is Modifierfalse
      Summaryfalse
      Alternate Namesinline resources, anonymous resources, contained resources
      14. CommunicationRequest.extension
      Definition

      May be used to represent additional information that is not part of the basic definition of the resource. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

      ShortAdditional content defined by implementations
      Comments

      There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

      Control0..*
      TypeExtension
      Is Modifierfalse
      Summaryfalse
      Alternate Namesextensions, user content
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
      16. CommunicationRequest.modifierExtension
      Definition

      May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

      Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

      ShortExtensions that cannot be ignored
      Comments

      There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

      Control0..*
      TypeExtension
      Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the resource that contains them
      Summaryfalse
      Requirements

      Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

      Alternate Namesextensions, user content
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
      18. CommunicationRequest.identifier
      Definition

      Business identifiers assigned to this communication request by the performer or other systems which remain constant as the resource is updated and propagates from server to server.

      ShortUnique identifier
      Comments

      This is a business identifier, not a resource identifier (see discussion). It is best practice for the identifier to only appear on a single resource instance, however business practices may occasionally dictate that multiple resource instances with the same identifier can exist - possibly even with different resource types. For example, multiple Patient and a Person resource instance might share the same social insurance number.

      NoteThis is a business identifier, not a resource identifier (see discussion)
      Control0..*
      TypeIdentifier
      Is Modifierfalse
      Summarytrue
      Requirements

      Allows identification of the communication request as it is known by various participating systems and in a way that remains consistent across servers.

      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      20. CommunicationRequest.basedOn
      Definition

      A plan or proposal that is fulfilled in whole or in part by this request.

      ShortFulfills plan or proposal
      Control0..*
      TypeReference(Resource)
      Is Modifierfalse
      Summarytrue
      Requirements

      Allows tracing of authorization for the request and tracking whether proposals/recommendations were acted upon.

      Alternate Namesfulfills
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      22. CommunicationRequest.replaces
      Definition

      Completed or terminated request(s) whose function is taken by this new request.

      ShortRequest(s) replaced by this request
      Comments

      The replacement could be because the initial request was immediately rejected (due to an issue) or because the previous request was completed, but the need for the action described by the request remains ongoing.

      Control0..*
      TypeReference(CommunicationRequest)
      Is Modifierfalse
      Summarytrue
      Requirements

      Allows tracing the continuation of a therapy or administrative process instantiated through multiple requests.

      Alternate Namessupersedes, prior
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      24. CommunicationRequest.groupIdentifier
      Definition

      A shared identifier common to all requests that were authorized more or less simultaneously by a single author, representing the identifier of the requisition, prescription or similar form.

      ShortComposite request this is part of
      Comments

      Requests are linked either by a "basedOn" relationship (i.e. one request is fulfilling another) or by having a common requisition. Requests that are part of the same requisition are generally treated independently from the perspective of changing their state or maintaining them after initial creation.

      Control0..1
      TypeIdentifier
      Is Modifierfalse
      Summarytrue
      Alternate NamesgrouperId
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      26. CommunicationRequest.status
      Definition

      The status of the proposal or order.

      Shortdraft | active | on-hold | revoked | completed | entered-in-error | unknown
      Control1..1
      BindingThe codes SHALL be taken from RequestStatus
      (required to http://hl7.org/fhir/ValueSet/request-status|4.0.1)

      The status of the communication request.

      Typecode
      Is Modifiertrue because This element is labelled as a modifier because it is a status element that contains status entered-in-error which means that the resource should not be treated as valid.
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Must Supporttrue
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      28. CommunicationRequest.statusReason
      Definition

      Captures the reason for the current state of the CommunicationRequest.

      ShortReason for current status
      Comments

      This is generally only used for "exception" statuses such as "suspended" or "cancelled". The reason why the CommunicationRequest was created at all is captured in reasonCode, not here. [distinct reason codes for different statuses can be enforced using invariants if they are universal bindings].

      Control0..1
      Binding

      Codes identifying the reason for the current state of a request.

      TypeCodeableConcept
      Is Modifierfalse
      Summaryfalse
      Alternate NamesSuspended Reason, Cancelled Reason
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      30. CommunicationRequest.category
      Definition

      The type of message to be sent such as alert, notification, reminder, instruction, etc.

      ShortMessage category
      Comments

      There may be multiple axes of categorization and one communication request may serve multiple purposes.

      Control0..*
      BindingFor example codes, see https://nhsdigital.github.io/nhs-notify-standards/fhir/ValueSet/nhsnotify-letter-category
      (example to https://nhsdigital.github.io/nhs-notify-standards/fhir/ValueSet/nhsnotify-letter-category)
      TypeCodeableConcept
      Is Modifierfalse
      Must Supporttrue
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      32. CommunicationRequest.priority
      Definition

      Characterizes how quickly the proposed act must be initiated. Includes concepts such as stat, urgent, routine.

      Shortroutine | urgent | asap | stat
      Control0..1
      BindingThe codes SHALL be taken from RequestPriority
      (required to http://hl7.org/fhir/ValueSet/request-priority|4.0.1)

      Codes indicating the relative importance of a communication request.

      Typecode
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Summarytrue
      Meaning if MissingIf missing, this task should be performed with normal priority
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      34. CommunicationRequest.doNotPerform
      Definition

      If true indicates that the CommunicationRequest is asking for the specified action to not occur.

      ShortTrue if request is prohibiting action
      Comments

      The attributes provided with the request qualify what is not to be done.

      Control0..1
      Typeboolean
      Is Modifiertrue because If true this element negates the specified action. For Example, instead of a request for a communication, it is a request for the communication to not occur.
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Summarytrue
      Alternate Namesprohibited
      Meaning if MissingIf do not perform is not specified, the request is a positive request e.g. "do perform"
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      36. CommunicationRequest.medium
      Definition

      A channel that was used for this communication (e.g. email, fax).

      ShortA channel of communication
      Control0..*
      BindingFor example codes, see ParticipationMode
      (example to http://terminology.hl7.org/ValueSet/v3-ParticipationMode)

      Codes for communication mediums such as phone, fax, email, in person, etc.

      TypeCodeableConcept
      Is Modifierfalse
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      38. CommunicationRequest.subject
      Definition

      The patient or group that is the focus of this communication request.

      ShortFocus of message
      Control1..1
      TypeReference(Patient)
      Is Modifierfalse
      Must Supporttrue
      Summaryfalse
      Alternate Namespatient
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      40. CommunicationRequest.subject.id
      Definition

      Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

      ShortUnique id for inter-element referencing
      Control0..1
      Typestring
      Is Modifierfalse
      XML FormatIn the XML format, this property is represented as an attribute.
      Summaryfalse
      42. CommunicationRequest.subject.extension
      Definition

      May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

      ShortAdditional content defined by implementations
      Comments

      There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

      Control0..*
      TypeExtension
      Is Modifierfalse
      Summaryfalse
      Alternate Namesextensions, user content
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
      SlicingThis element introduces a set of slices on CommunicationRequest.subject.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
      • value @ url
      • 44. CommunicationRequest.subject.reference
        Definition

        A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.

        ShortLiteral reference, Relative, internal or absolute URL
        Comments

        Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "/[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.

        Control0..1
        This element is affected by the following invariants: ref-1
        Typestring
        Is Modifierfalse
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        46. CommunicationRequest.subject.type
        Definition

        The expected type of the target of the reference. If both Reference.type and Reference.reference are populated and Reference.reference is a FHIR URL, both SHALL be consistent.

        The type is the Canonical URL of Resource Definition that is the type this reference refers to. References are URLs that are relative to http://hl7.org/fhir/StructureDefinition/ e.g. "Patient" is a reference to http://hl7.org/fhir/StructureDefinition/Patient. Absolute URLs are only allowed for logical models (and can only be used in references in logical models, not resources).

        ShortType the reference refers to (e.g. "Patient")
        Comments

        This element is used to indicate the type of the target of the reference. This may be used which ever of the other elements are populated (or not). In some cases, the type of the target may be determined by inspection of the reference (e.g. a RESTful URL) or by resolving the target of the reference; if both the type and a reference is provided, the reference SHALL resolve to a resource of the same type as that specified.

        Control0..1
        BindingUnless not suitable, these codes SHALL be taken from ResourceType
        (extensible to http://hl7.org/fhir/ValueSet/resource-types|4.0.1)

        Aa resource (or, for logical models, the URI of the logical model).

        Typeuri
        Is Modifierfalse
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        48. CommunicationRequest.subject.identifier
        Definition

        An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

        ShortNHS Number used to identify the patient
        Comments

        When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.

        When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference

        Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.

        Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

        NoteThis is a business identifier, not a resource identifier (see discussion)
        Control0..1
        TypeIdentifier
        Is Modifierfalse
        Must Supporttrue
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        50. CommunicationRequest.subject.identifier.id
        Definition

        Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

        ShortUnique id for inter-element referencing
        Control0..1
        Typestring
        Is Modifierfalse
        XML FormatIn the XML format, this property is represented as an attribute.
        Summaryfalse
        52. CommunicationRequest.subject.identifier.extension
        Definition

        May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

        ShortAdditional content defined by implementations
        Comments

        There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

        Control0..*
        TypeExtension
        Is Modifierfalse
        Summaryfalse
        Alternate Namesextensions, user content
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
        SlicingThis element introduces a set of slices on CommunicationRequest.subject.identifier.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
        • value @ url
        • 54. CommunicationRequest.subject.identifier.use
          Definition

          The purpose of this identifier.

          Shortusual | official | temp | secondary | old (If known)
          Comments

          Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.

          Control0..1
          BindingThe codes SHALL be taken from IdentifierUse
          (required to http://hl7.org/fhir/ValueSet/identifier-use|4.0.1)

          Identifies the purpose for this identifier, if known .

          Typecode
          Is Modifiertrue because This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one.
          Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
          Summarytrue
          Requirements

          Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.

          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          56. CommunicationRequest.subject.identifier.type
          Definition

          A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.

          ShortDescription of identifier
          Comments

          This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage. Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.

          Control0..1
          BindingUnless not suitable, these codes SHALL be taken from Identifier Type Codes
          (extensible to http://hl7.org/fhir/ValueSet/identifier-type|4.0.1)

          A coded type for an identifier that can be used to determine which identifier to use for a specific purpose.

          TypeCodeableConcept
          Is Modifierfalse
          Summarytrue
          Requirements

          Allows users to make use of identifiers when the identifier system is not known.

          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          58. CommunicationRequest.subject.identifier.system
          Definition

          Establishes the namespace for the value - that is, a URL that describes a set values that are unique.

          ShortThe namespace for the identifier value
          Comments

          Identifier.system is always case sensitive.

          Control0..1
          Typeuri
          Is Modifierfalse
          Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
          Summarytrue
          Requirements

          There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.

          Fixed Valuehttps://fhir.nhs.uk/Id/nhs-number
          ExampleGeneral: http://www.acme.com/identifiers/patient
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          60. CommunicationRequest.subject.identifier.value
          Definition

          The portion of the identifier typically relevant to the user and which is unique within the context of the system.

          ShortThe value that is unique
          Comments

          If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the Rendered Value extension. Identifier.value is to be treated as case sensitive unless knowledge of the Identifier.system allows the processer to be confident that non-case-sensitive processing is safe.

          Control0..1
          Typestring
          Is Modifierfalse
          Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
          Summarytrue
          ExampleGeneral: 123456
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          62. CommunicationRequest.subject.identifier.period
          Definition

          Time period during which identifier is/was valid for use.

          ShortTime period when id is/was valid for use
          Control0..1
          TypePeriod
          Is Modifierfalse
          Summarytrue
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          64. CommunicationRequest.subject.identifier.assigner
          Definition

          Organization that issued/manages the identifier.

          ShortOrganization that issued id (may be just text)
          Comments

          The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.

          Control0..1
          TypeReference(Organization)
          Is Modifierfalse
          Summarytrue
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          66. CommunicationRequest.subject.display
          Definition

          Plain text narrative that identifies the resource in addition to the resource reference.

          ShortText alternative for the resource
          Comments

          This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.

          Control0..1
          Typestring
          Is Modifierfalse
          Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
          Summarytrue
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          68. CommunicationRequest.about
          Definition

          Other resources that pertain to this communication request and to which this communication request should be associated.

          ShortResources that pertain to this communication request
          Comments

          Don't use CommunicationRequest.about element when a more specific element exists, such as basedOn, reasonReference, or replaces.

          Control0..*
          TypeReference(Resource)
          Is Modifierfalse
          Summaryfalse
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          70. CommunicationRequest.encounter
          Definition

          The Encounter during which this CommunicationRequest was created or to which the creation of this record is tightly associated.

          ShortEncounter created as part of
          Comments

          This will typically be the encounter the event occurred within, but some activities may be initiated prior to or after the official completion of an encounter but still be tied to the context of the encounter.

          Control0..1
          TypeReference(Encounter)
          Is Modifierfalse
          Summarytrue
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          72. CommunicationRequest.payload
          Definition

          Text, attachment(s), or resource(s) to be communicated to the recipient.

          ShortAt least one letter payload (PDF metadata via DocumentReference)
          Control1..*
          TypeBackboneElement
          Is Modifierfalse
          Must Supporttrue
          Summaryfalse
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          74. CommunicationRequest.payload.id
          Definition

          Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

          ShortUnique id for inter-element referencing
          Control0..1
          Typestring
          Is Modifierfalse
          XML FormatIn the XML format, this property is represented as an attribute.
          Summaryfalse
          76. CommunicationRequest.payload.extension
          Definition

          May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

          ShortAdditional content defined by implementations
          Comments

          There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

          Control0..*
          TypeExtension
          Is Modifierfalse
          Summaryfalse
          Alternate Namesextensions, user content
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
          78. CommunicationRequest.payload.modifierExtension
          Definition

          May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

          Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

          ShortExtensions that cannot be ignored even if unrecognized
          Comments

          There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

          Control0..*
          TypeExtension
          Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the element that contains them
          Summarytrue
          Requirements

          Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

          Alternate Namesextensions, user content, modifiers
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
          80. CommunicationRequest.payload.content[x]
          Definition

          The communicated content (or for multi-part communications, one portion of the communication).

          ShortMessage part content
          Control1..1
          TypeReference(Resource)
          [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
          Is Modifierfalse
          Summaryfalse
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          SlicingThis element introduces a set of slices on CommunicationRequest.payload.content[x]. The slices areUnordered and Closed, and can be differentiated using the following discriminators:
          • type @ $this
          • 82. CommunicationRequest.payload.content[x]:contentReference
            Slice NamecontentReference
            Definition

            The communicated content (or for multi-part communications, one portion of the communication).

            ShortDocumentReference wrapping the PDF binary
            Control1..1
            TypeReference(Letter PDF Document)
            [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
            Is Modifierfalse
            Must Supporttrue
            Summaryfalse
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            84. CommunicationRequest.occurrence[x]
            Definition

            The time when this communication is to occur.

            ShortWhen scheduled
            Control0..1
            TypeChoice of: dateTime, Period
            [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
            Is Modifierfalse
            Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
            Summarytrue
            Alternate Namestiming
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            86. CommunicationRequest.authoredOn
            Definition

            For draft requests, indicates the date of initial creation. For requests with other statuses, indicates the date of activation.

            ShortWhen the request was authored
            Control0..1
            TypedateTime
            Is Modifierfalse
            Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
            Must Supporttrue
            Summarytrue
            Alternate NamescreatedOn
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            88. CommunicationRequest.requester
            Definition

            The device, individual, or organization who initiated the request and has responsibility for its activation.

            ShortSubmitting system or responsible party
            Control1..1
            TypeReference(Practitioner, PractitionerRole, Organization, Patient, RelatedPerson, Device)
            Is Modifierfalse
            Must Supporttrue
            Must Support TypesNo must-support rules about the choice of types/profiles
            Summarytrue
            Alternate Namesauthor
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            90. CommunicationRequest.recipient
            Definition

            The entity (e.g. person, organization, clinical information system, device, group, or care team) which is the intended target of the communication.

            ShortIntended recipient entity (e.g. print fulfilment endpoint)
            Control1..*
            TypeReference(Device, Organization, Patient, Practitioner, PractitionerRole, RelatedPerson, Group, CareTeam, HealthcareService)
            Is Modifierfalse
            Must Supporttrue
            Must Support TypesNo must-support rules about the choice of types/profiles
            Summaryfalse
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            92. CommunicationRequest.sender
            Definition

            The entity (e.g. person, organization, clinical information system, or device) which is to be the source of the communication.

            ShortSource organization (ODS code)
            Control0..1
            TypeReference(Device, Organization, Patient, Practitioner, PractitionerRole, RelatedPerson, HealthcareService)
            Is Modifierfalse
            Must Supporttrue
            Must Support TypesNo must-support rules about the choice of types/profiles
            Summarytrue
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            94. CommunicationRequest.reasonCode
            Definition

            Describes why the request is being made in coded or textual form.

            ShortWhy is communication needed?
            Comments

            Textual reasons can be captured using reasonCode.text.

            Control0..*
            BindingFor example codes, see v3 Code System ActReason
            (example to http://terminology.hl7.org/ValueSet/v3-ActReason)

            Codes for describing reasons for the occurrence of a communication.

            TypeCodeableConcept
            Is Modifierfalse
            Summarytrue
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            96. CommunicationRequest.reasonReference
            Definition

            Indicates another resource whose existence justifies this request.

            ShortWhy is communication needed?
            Control0..*
            TypeReference(Condition, Observation, DiagnosticReport, DocumentReference)
            Is Modifierfalse
            Summarytrue
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            98. CommunicationRequest.note
            Definition

            Comments made about the request by the requester, sender, recipient, subject or other participants.

            ShortComments made about communication request
            Control0..*
            TypeAnnotation
            Is Modifierfalse
            Summaryfalse
            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))