A record of an event relevant for purposes such as operations, privacy, security, maintenance, and performance analysis.

Based on IHE-ATNA.

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.

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 its narrative along with other profiles, value sets, etc.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, nor can they have their own independent transaction scope. This is allowed to be a Parameters resource if and only if it is referenced by a resource that provides context/meaning.

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.

An Extension

DSTU2: AuditEvent.event.outcomeDesc (new:string)

Element AuditEvent.event.outcomeDesc has a context of AuditEvent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.event.outcomeDesc has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

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 managable, 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).

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.

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.

Describes what happened. The most specific code for the event.

For example codes, see AuditEventSubType http://hl7.org/fhir/ValueSet/audit-event-sub-type|5.0.0
(example to http://hl7.org/fhir/ValueSet/audit-event-sub-type|5.0.0)

Specific type of event.

This field enables queries of messages by implementation-defined event categories.

The time when the event was recorded.

In a distributed system, some sort of common time base (e.g. an NTP [RFC1305] server) is a good implementation tactic.

This ties an event to a specific date and time. Security audits typically require a consistent time base (e.g. UTC), to eliminate time-zone issues arising from geographical distribution.

An actor taking an active role in the event or activity that is logged.

Several agents may be associated (i.e. have some responsibility for an activity) with an event or activity.

For example, an activity may be initiated by one user for other users or involve more than one user. However, only one user may be the initiator/requestor for the activity.

When a network are used in an event being recorded, there should be distinct agent elements for the known actors using the network. The agent with a network detail would be the responsible agent for use of that network.

An agent can be a person, an organization, software, device, or other actors that may be ascribed responsibility.

An Extension

DSTU2: AuditEvent.participant.userId (new:Identifier)

Element AuditEvent.participant.userId has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.userId has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). a unique value within the Audit Source ID. For node-based authentication -- where only the system hardware or process, but not a human user, is identified -- User ID would be the node name.

DSTU2: AuditEvent.participant.altId (new:string)

Element AuditEvent.participant.altId has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.altId has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.name (new:string)

Element AuditEvent.participant.name has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.name has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.media (new:Coding)

Element AuditEvent.participant.media has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.media has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.network.address (new:string)

Element AuditEvent.participant.network.address has a context of AuditEvent.agent.network[x] based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.network.address has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). The target context AuditEvent.agent.network[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element AuditEvent.agent. This could be a device id, IP address or some other identifier associated with a device.

DSTU2: AuditEvent.participant.network.type (new:code)

Element AuditEvent.participant.network.type has a context of AuditEvent.agent.network[x] based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.network.type has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). The target context AuditEvent.agent.network[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element AuditEvent.agent.

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 managable, 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).

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.

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.

Reference to who this agent is that was involved in the event.

Where a User ID is available it will go into who.identifier. Where a name of the user (human readable) it will go into who.display.

This field ties an audit event to a specific resource or identifier.

An Extension

DSTU2: AuditEvent.participant.reference

Element AuditEvent.participant.reference is mapped to FHIR R5 element AuditEvent.agent.who as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR DSTU2 element AuditEvent.participant.reference with unmapped reference targets: Device, Organization, Patient, Practitioner, RelatedPerson.

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.

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.

The actor that is reporting the event.

Events are reported by the actor that detected them. This may be one of the participating actors, but may also be different. The actor may be a human such as a medical-records clerk disclosing data manually, that clerk would be the source for the record of disclosure.

The event is reported by one source.

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 managable, 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).

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.

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.

Identifier of the source where the event was detected.

This field ties the event to a specific source system. It may be used to group events for analysis according to where the event was detected.

An Extension

DSTU2: AuditEvent.source.identifier additional types (Identifier) additional types from child elements (period, system, type, use, value)

Element AuditEvent.source.identifier is mapped to FHIR R5 element AuditEvent.source.observer as SourceIsBroaderThanTarget. The mappings for AuditEvent.source.identifier do not cover the following types: Identifier. The mappings for AuditEvent.source.identifier do not cover the following types based on type expansion: period, system, type, use, value.

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.

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.

DSTU2: AuditEvent.meta additional types (Meta) additional types from child elements (lastUpdated, profile, security, tag, versionId)

Element AuditEvent.meta is mapped to FHIR R5 element AuditEvent.meta as SourceIsBroaderThanTarget. The mappings for AuditEvent.meta do not cover the following types: Meta. The mappings for AuditEvent.meta do not cover the following types based on type expansion: lastUpdated, profile, security, tag, versionId.

DSTU2: AuditEvent.text additional types (Narrative) additional types from child elements (div, status)

Element AuditEvent.text is mapped to FHIR R5 element AuditEvent.text as SourceIsBroaderThanTarget. The mappings for AuditEvent.text do not cover the following types: Narrative. The mappings for AuditEvent.text do not cover the following types based on type expansion: div, status. Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative.

DSTU2: AuditEvent.event.outcomeDesc (new:string)

Element AuditEvent.event.outcomeDesc has a context of AuditEvent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.event.outcomeDesc has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.event.outcome additional codes

Element AuditEvent.event.outcome is mapped to FHIR R5 element AuditEvent.outcome.code as SourceIsNarrowerThanTarget. The mappings for AuditEvent.event.outcome do not allow expression of the necessary codes, per the bindings on the source and target. In some cases a "success" may be partial, for example, an incomplete or interrupted transfer of a radiological study. For the purpose of establishing accountability, these distinctions are not relevant.

DSTU2: AuditEvent.participant.userId (new:Identifier)

Element AuditEvent.participant.userId has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.userId has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). a unique value within the Audit Source ID. For node-based authentication -- where only the system hardware or process, but not a human user, is identified -- User ID would be the node name.

DSTU2: AuditEvent.participant.altId (new:string)

Element AuditEvent.participant.altId has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.altId has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.name (new:string)

Element AuditEvent.participant.name has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.name has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.media (new:Coding)

Element AuditEvent.participant.media has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.media has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.network.address (new:string)

Element AuditEvent.participant.network.address has a context of AuditEvent.agent.network[x] based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.network.address has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). The target context AuditEvent.agent.network[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element AuditEvent.agent. This could be a device id, IP address or some other identifier associated with a device.

DSTU2: AuditEvent.participant.network.type (new:code)

Element AuditEvent.participant.network.type has a context of AuditEvent.agent.network[x] based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.network.type has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). The target context AuditEvent.agent.network[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element AuditEvent.agent.

DSTU2: AuditEvent.participant.reference

Element AuditEvent.participant.reference is mapped to FHIR R5 element AuditEvent.agent.who as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR DSTU2 element AuditEvent.participant.reference with unmapped reference targets: Device, Organization, Patient, Practitioner, RelatedPerson.

DSTU2: AuditEvent.participant.location additional types from child elements (display, reference)

Element AuditEvent.participant.location is mapped to FHIR R5 element AuditEvent.agent.location as SourceIsBroaderThanTarget. The mappings for AuditEvent.participant.location do not cover the following types based on type expansion: display, reference. The standard extension alternate-reference has been mapped as the representation of FHIR DSTU2 element AuditEvent.participant.location with unmapped reference targets: Location.

DSTU2: AuditEvent.source.site additional types (string) additional types from child elements (value)

Element AuditEvent.source.site is mapped to FHIR R5 element AuditEvent.source.site as SourceIsBroaderThanTarget. The mappings for AuditEvent.source.site do not cover the following types: string. The mappings for AuditEvent.source.site do not cover the following types based on type expansion: value.

DSTU2: AuditEvent.source.identifier additional types (Identifier) additional types from child elements (period, system, type, use, value)

Element AuditEvent.source.identifier is mapped to FHIR R5 element AuditEvent.source.observer as SourceIsBroaderThanTarget. The mappings for AuditEvent.source.identifier do not cover the following types: Identifier. The mappings for AuditEvent.source.identifier do not cover the following types based on type expansion: period, system, type, use, value.

DSTU2: AuditEvent.object.type (new:Coding)

Element AuditEvent.object.type has a context of AuditEvent.entity based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.object.type has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). This value is distinct from the user's role or any user relationship to the participant object.

DSTU2: AuditEvent.object.lifecycle (new:Coding)

Element AuditEvent.object.lifecycle has a context of AuditEvent.entity based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.object.lifecycle has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). This can be used to provide an audit trail for data, over time, as it passes through the system.

DSTU2: AuditEvent.object.name (new:string)

Element AuditEvent.object.name has a context of AuditEvent.entity based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.object.name has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). This field may be used in a query/report to identify audit events for a specific person. For example, where multiple synonymous Participant Object IDs (patient number, medical record number, encounter number, etc.) have been used.

DSTU2: AuditEvent.object.description (new:string)

Element AuditEvent.object.description has a context of AuditEvent.entity based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.object.description has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.object.identifier additional types (Identifier) additional types from child elements (period, system, type, use, value)

Element AuditEvent.object.identifier is mapped to FHIR R5 element AuditEvent.entity.what as SourceIsBroaderThanTarget. The mappings for AuditEvent.object.identifier do not cover the following types: Identifier. The mappings for AuditEvent.object.identifier do not cover the following types based on type expansion: period, system, type, use, value. Identifier detail depends on object type.

DSTU2: AuditEvent.object.reference additional types from child elements (display, reference)

Element AuditEvent.object.reference is mapped to FHIR R5 element AuditEvent.entity.what as SourceIsBroaderThanTarget. The mappings for AuditEvent.object.reference do not cover the following types based on type expansion: display, reference. The standard extension alternate-reference has been mapped as the representation of FHIR DSTU2 element AuditEvent.object.reference with unmapped reference targets: Resource.

DSTU2: AuditEvent.object.detail.type additional types (string) additional types from child elements (value)

Element AuditEvent.object.detail.type is mapped to FHIR R5 element AuditEvent.entity.detail.type as SourceIsBroaderThanTarget. The mappings for AuditEvent.object.detail.type do not cover the following types: string. The mappings for AuditEvent.object.detail.type do not cover the following types based on type expansion: value.

A record of an event relevant for purposes such as operations, privacy, security, maintenance, and performance analysis.

Based on IHE-ATNA.

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

Within the context of the FHIR RESTful interactions, the resource has an id except for cases like the create and conditional update. Otherwise, the use of the resouce id depends on the given use case.

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.

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

An Extension

DSTU2: AuditEvent.meta additional types (Meta) additional types from child elements (lastUpdated, profile, security, tag, versionId)

Element AuditEvent.meta is mapped to FHIR R5 element AuditEvent.meta as SourceIsBroaderThanTarget. The mappings for AuditEvent.meta do not cover the following types: Meta. The mappings for AuditEvent.meta do not cover the following types based on type expansion: lastUpdated, profile, security, tag, versionId.

The version specific identifier, as it appears in the version portion of the URL. This value changes when the resource is created, updated, or deleted.

The server assigns this value, and ignores what the client specifies, except in the case that the server is imposing version integrity on updates/deletes.

When the resource last changed - e.g. when the version changed.

This element is generally omitted in instances submitted in a PUT or POST. Instead, it is populated in the response instance and when retrieving information using a GET. The server / resource manager sets this value; what a client provides is irrelevant. This is equivalent to the HTTP Last-Modified and SHOULD have the same value on a read interaction.

A uri that identifies the source system of the resource. This provides a minimal amount of Provenance information that can be used to track or differentiate the source of information in the resource. The source may identify another FHIR server, document, message, database, etc.

The exact use of the source (and the possible implied Provenance.entity.role and agent.role) is left to implementer discretion. Only one nominated source is allowed; for additional provenance details, a full Provenance resource should be used. The source may correspond to Provenance.entity.what[x] or Provenance.agent.who[x], though it may be a more general or abstract reference.

This element can be used to indicate where the current master source of a resource that has a canonical URL if the resource is no longer hosted at the canonical URL.

A list of profiles (references to StructureDefinition resources) that this resource claims to conform to. The URL is a reference to StructureDefinition.url.

It is up to the server and/or other infrastructure of policy to determine whether/how these claims are verified and/or updated over time. The list of profile URLs is a set.

Security labels applied to this resource. These tags connect specific resources to the overall security policy and infrastructure.

The security labels can be updated without changing the stated version of the resource. The list of security labels is a set. Uniqueness is based the system/code, and version and display are ignored.

Unless not suitable, these codes SHALL be taken from AllSecurityLabels
(extensible to http://hl7.org/fhir/ValueSet/security-labels|5.0.0)

Security Labels from the Healthcare Privacy and Security Classification System.

Tags applied to this resource. Tags are intended to be used to identify and relate resources to process and workflow, and applications are not required to consider the tags when interpreting the meaning of a resource.

The tags can be updated without changing the stated version of the resource. The list of tags is a set. Uniqueness is based the system/code, and version and display are ignored.

Codes that represent various types of tags, commonly workflow-related; e.g. "Needs review by Dr. Jones".

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.

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 its narrative along with other profiles, value sets, etc.

The base language in which the resource is written.

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).

IETF language tag for a human language

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.

Contained resources do not have a 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.

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

An Extension

DSTU2: AuditEvent.text additional types (Narrative) additional types from child elements (div, status)

Element AuditEvent.text is mapped to FHIR R5 element AuditEvent.text as SourceIsBroaderThanTarget. The mappings for AuditEvent.text do not cover the following types: Narrative. The mappings for AuditEvent.text do not cover the following types based on type expansion: div, status. Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative.

The status of the narrative - whether it's entirely generated (from just the defined data or the extensions too), or whether a human authored it and it may contain additional data.

The status of a resource narrative.

The actual narrative content, a stripped down version of XHTML.

The contents of the html element are an XHTML fragment containing only the basic html formatting elements described in chapters 7-11 and 15 of the HTML 4.0 standard, <a> elements (either name or href), images and internally contained stylesheets. The XHTML content SHALL NOT contain a head, a body, external stylesheet references, scripts, forms, base/link/xlink, frames, iframes and objects.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, nor can they have their own independent transaction scope. This is allowed to be a Parameters resource if and only if it is referenced by a resource that provides context/meaning.

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.

An Extension

DSTU2: AuditEvent.event.outcomeDesc (new:string)

Element AuditEvent.event.outcomeDesc has a context of AuditEvent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.event.outcomeDesc has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

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 managable, 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).

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.

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.

Classification of the type of event.

Type of event.

Codes that classify the general type of event that happened.

Describes what happened. The most specific code for the event.

For example codes, see AuditEventSubType
(example to http://hl7.org/fhir/ValueSet/audit-event-sub-type|5.0.0)

Specific type of event.

This field enables queries of messages by implementation-defined event categories.

Indicator for type of action performed during the event that generated the audit.

DICOM Audit Event Action

This broadly indicates what kind of action was done on the AuditEvent.entity by the AuditEvent.agent.

Indicates and enables segmentation of various severity including debugging from critical.

ATNA will map this to the SYSLOG PRI element.

This is in the SysLog header, PRI. http://tools.ietf.org/html/rfc5424#appendix-A.3

The time or period during which the activity occurred.

The time or period can be a little arbitrary; where possible, the time should correspond to human assessment of the activity time.

The time when the event was recorded.

In a distributed system, some sort of common time base (e.g. an NTP [RFC1305] server) is a good implementation tactic.

This ties an event to a specific date and time. Security audits typically require a consistent time base (e.g. UTC), to eliminate time-zone issues arising from geographical distribution.

Indicates whether the event succeeded or failed. A free text descripiton can be given in outcome.text.

In some cases a "success" may be partial, for example, an incomplete or interrupted transfer of a radiological study. For the purpose of establishing accountability, these distinctions are not relevant.

when a code is given there must be one code from the given codeSystem, and may be other equivilant codes from other codeSystems (for example http response codes such as 2xx, 4xx, or 5xx).

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

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 managable, 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.

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.

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 managable, 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).

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.

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.

Indicates whether the event succeeded or failed.

In some cases a "success" may be partial, for example, an incomplete or interrupted transfer of a radiological study. For the purpose of establishing accountability, these distinctions are not relevant.

DICOM Audit Event Outcome

when a code is given there must be one code from the given codeSystem.

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

An Extension

DSTU2: AuditEvent.event.outcome additional codes

Element AuditEvent.event.outcome is mapped to FHIR R5 element AuditEvent.outcome.code as SourceIsNarrowerThanTarget. The mappings for AuditEvent.event.outcome do not allow expression of the necessary codes, per the bindings on the source and target. In some cases a "success" may be partial, for example, an incomplete or interrupted transfer of a radiological study. For the purpose of establishing accountability, these distinctions are not relevant.

The identification of the code system that defines the meaning of the symbol in the code.

The URI may be an OID (urn:oid:...) or a UUID (urn:uuid:...). OIDs and UUIDs SHALL be references to the HL7 OID registry. Otherwise, the URI should come from HL7's list of FHIR defined special URIs or it should be an absolute reference to some definition that establishes the system clearly and unambiguously.

Need to be unambiguous about the source of the definition of the symbol.

The version of the code system which was used when choosing this code. Note that a well-maintained code system does not need the version reported, because the meaning of codes is consistent across versions. However this cannot consistently be assured, and when the meaning is not guaranteed to be consistent, the version SHOULD be exchanged.

Where the terminology does not clearly define what string should be used to identify code system versions, the recommendation is to use the date (expressed in FHIR date format) on which that version was officially published as the version date.

A symbol in syntax defined by the system. The symbol may be a predefined code or an expression in a syntax defined by the coding system (e.g. post-coordination).

Need to refer to a particular code in the system.

A representation of the meaning of the code in the system, following the rules of the system.

Need to be able to carry a human-readable meaning of the code for readers that do not know the system.

Indicates that this coding was chosen by a user directly - e.g. off a pick list of available items (codes or displays).

Amongst a set of alternatives, a directly chosen code is the most appropriate starting point for new translations. There is some ambiguity about what exactly 'directly chosen' implies, and trading partner agreement may be needed to clarify the use of this element and its consequences more completely.

This has been identified as a clinical safety criterium - that this exact system/code pair was chosen explicitly, rather than inferred by the system based on some rules or language processing.

Additional details about the error. This may be a text description of the error or a system code that identifies the error.

A human readable description of the error issue SHOULD be placed in details.text.

A code that provides details as the exact issue.

The authorization (e.g., PurposeOfUse) that was used during the event being recorded.

Use AuditEvent.agent.authorization when you know that it is specific to the agent, otherwise use AuditEvent.authorization. For example, during a machine-to-machine transfer it might not be obvious to the audit system who caused the event, but it does know why.

The authorized purposeOfUse for the activity.

Record of any relevant security context, not restricted to purposeOfUse valueSet. May include security compartments, refrain, obligation, or other security tags.

Allows tracing of authorizatino for the events and tracking whether proposals/recommendations were acted upon.

The patient element is available to enable deterministic tracking of activities that involve the patient as the subject of the data used in an activity.

When the .patient is populated it shall be accurate to the subject of the used data. The .patient shall not be populated when the used data used/created/updated/deleted (.entity) by the activity does not involve a subject. Note that when the patient is an agent, they will be recorded as an agent. When the Patient resource is Created, Updated, or Deleted it will be recorded as an entity.

This will typically be the encounter the event occurred, but some events may be initiated prior to or after the official completion of an encounter but still be tied to the context of the encounter (e.g. pre-admission lab tests).

An actor taking an active role in the event or activity that is logged.

Several agents may be associated (i.e. have some responsibility for an activity) with an event or activity.

For example, an activity may be initiated by one user for other users or involve more than one user. However, only one user may be the initiator/requestor for the activity.

When a network are used in an event being recorded, there should be distinct agent elements for the known actors using the network. The agent with a network detail would be the responsible agent for use of that network.

An agent can be a person, an organization, software, device, or other actors that may be ascribed responsibility.

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

An Extension

DSTU2: AuditEvent.participant.userId (new:Identifier)

Element AuditEvent.participant.userId has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.userId has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). a unique value within the Audit Source ID. For node-based authentication -- where only the system hardware or process, but not a human user, is identified -- User ID would be the node name.

DSTU2: AuditEvent.participant.altId (new:string)

Element AuditEvent.participant.altId has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.altId has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.name (new:string)

Element AuditEvent.participant.name has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.name has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.media (new:Coding)

Element AuditEvent.participant.media has a context of AuditEvent.agent based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.media has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

DSTU2: AuditEvent.participant.network.address (new:string)

Element AuditEvent.participant.network.address has a context of AuditEvent.agent.network[x] based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.network.address has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). The target context AuditEvent.agent.network[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element AuditEvent.agent. This could be a device id, IP address or some other identifier associated with a device.

DSTU2: AuditEvent.participant.network.type (new:code)

Element AuditEvent.participant.network.type has a context of AuditEvent.agent.network[x] based on following the parent source element upwards and mapping to AuditEvent. Element AuditEvent.participant.network.type has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element). The target context AuditEvent.agent.network[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element AuditEvent.agent.

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 managable, 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).

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.

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.

The Functional Role of the user when performing the event.

For example: assembler, author, prescriber, signer, investigator, etc.

The Participation type of the agent to the event.

Functional roles reflect functional aspects of relationships between entities. Functional roles are bound to the realization/performance of acts, where actions might be concatenated to an activity or even to a process. This element will hold the functional role that the agent played in the activity that is the focus of this Provenance. Where an agent played multiple functional roles, they will be listed as multiple .agent elements representing each functional participation. See ISO 21298:2018 - Health Informatics - Functional and structural roles, and ISO 22600-2:2014 - Health Informatics - Privilege Management and Access Control - Part 2: formal models.

The structural roles of the agent indicating the agent's competency. The security role enabling the agent with respect to the activity.

For example: Chief-of-Radiology, Nurse, Physician, Medical-Student, etc.

What security role enabled the agent to participate in the event.

Structural roles reflect the structural aspects of relationships between entities. Structural roles describe prerequisites, feasibilities, or competences for acts. Functional roles reflect functional aspects of relationships between entities. Functional roles are bound to the realization/performance of acts, where actions might be concatenated to an activity or even to a process. See ISO 21298:2018 - Health Informatics - Functional and structural roles, and ISO 22600-2:2014 - Health Informatics - Privilege Management and Access Control - Part 2: formal models..

Reference to who this agent is that was involved in the event.

Where a User ID is available it will go into who.identifier. Where a name of the user (human readable) it will go into who.display.

This field ties an audit event to a specific resource or identifier.

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

An Extension

DSTU2: AuditEvent.participant.reference

Element AuditEvent.participant.reference is mapped to FHIR R5 element AuditEvent.agent.who as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR DSTU2 element AuditEvent.participant.reference with unmapped reference targets: Device, Organization, Patient, Practitioner, RelatedPerson.

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.

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.

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).

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 known RESTful URL) or by resolving the target of the reference.

Unless not suitable, these codes SHALL be taken from ResourceType
(extensible to http://hl7.org/fhir/ValueSet/resource-types|5.0.0)

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

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.

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).

This element only allows for a single identifier. In the case where additional identifers are required, use the http://hl7.org/fhir/StructureDefinition/additionalIdentifier extension.

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

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.

Indicator that the user is or is not the requestor, or initiator, for the event being audited.

There can only be one initiator. If the initiator is not clear, then do not choose any one agent as the initiator.

This value is used to distinguish between requestor-users and recipient-users. For example, one person may initiate a report-output to be sent to another user.

Where the agent location is known, the agent location when the event occurred.

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

An Extension

DSTU2: AuditEvent.participant.location additional types from child elements (display, reference)

Element AuditEvent.participant.location is mapped to FHIR R5 element AuditEvent.agent.location as SourceIsBroaderThanTarget. The mappings for AuditEvent.participant.location do not cover the following types based on type expansion: display, reference. The standard extension alternate-reference has been mapped as the representation of FHIR DSTU2 element AuditEvent.participant.location with unmapped reference targets: Location.

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.

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.

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).

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 known RESTful URL) or by resolving the target of the reference.

Unless not suitable, these codes SHALL be taken from ResourceType
(extensible to http://hl7.org/fhir/ValueSet/resource-types|5.0.0)

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

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.

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).

This element only allows for a single identifier. In the case where additional identifers are required, use the http://hl7.org/fhir/StructureDefinition/additionalIdentifier extension.

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

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.

Where the policy(ies) are known that authorized the agent participation in the event. Typically, a single activity may have multiple applicable policies, such as patient consent, guarantor funding, etc. The policy would also indicate the security token used.

For example: Where an OAuth token authorizes, the unique identifier from the OAuth token is placed into the policy element Where a policy engine (e.g. XACML) holds policy logic, the unique policy identifier is placed into the policy element.

This value is used retrospectively to determine the authorization policies.

When the event utilizes a network there should be an agent describing the local system, and an agent describing remote system, with the network interface details.

When remote network endpoint is known, another agent representing the remote agent would indicate the remote network endpoint used. Convention is to indicate data flowing from Source to Destination. The convention for Search, given data flows both ways (query parameters vs results), is to have the Source as the initiator of the Search Transaction, and the Destination the responder to the Search transaction.

When a network protocol is used the endpoint is associated with the agent most directly using the endpoint. This is usually the software agent that has implemented the application level protocol. Preference is to define network in terms of a Reference(Endpoint), or URI; use string only when address or hostname is all that is known. When encoding using string it is best to encode using the formal canonical host name, but if you can't, then you can encode numeric in Literal address form using square brackets '[]' as a v4 string (in dotted notation), or v6 string (in colon notation).

The authorization (e.g., PurposeOfUse) that was used during the event being recorded.

Use AuditEvent.agent.authorization when you know that is specific to the agent, otherwise use AuditEvent.authorization. For example, during a machine-to-machine transfer it might not be obvious to the audit system who caused the event, but it does know why.

The reason the activity took place.

Record of any relevant security context, not restricted to purposeOfUse valueSet. May include security compartments, refrain, obligation, or other security tags.

The actor that is reporting the event.

Events are reported by the actor that detected them. This may be one of the participating actors, but may also be different. The actor may be a human such as a medical-records clerk disclosing data manually, that clerk would be the source for the record of disclosure.

The event is reported by one source.

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

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 managable, 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.

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.

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 managable, 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).

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.

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.

Logical source location within the healthcare enterprise network. For example, a hospital or other provider location within a multi-entity provider group.

This value differentiates among the sites in a multi-site enterprise health information system.

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

An Extension

DSTU2: AuditEvent.source.site additional types (string) additional types from child elements (value)

Element AuditEvent.source.site is mapped to FHIR R5 element AuditEvent.source.site as SourceIsBroaderThanTarget. The mappings for AuditEvent.source.site do not cover the following types: string. The mappings for AuditEvent.source.site do not cover the following types based on type expansion: value.

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.

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.

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).

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 known RESTful URL) or by resolving the target of the reference.

Unless not suitable, these codes SHALL be taken from ResourceType
(extensible to http://hl7.org/fhir/ValueSet/resource-types|5.0.0)

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

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.

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).

This element only allows for a single identifier. In the case where additional identifers are required, use the http://hl7.org/fhir/StructureDefinition/additionalIdentifier extension.

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

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.

Identifier of the source where the event was detected.

This field ties the event to a specific source system. It may be used to group events for analysis according to where the event was detected.

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

An Extension