Reference

$10 / year

Many of the defined elements in a resource are references to other resources. Using these references, the resources combine to build a web of information about healthcare.

Complexity

References are always defined and represented in one direction – from one resource (source) to another (target). The corresponding reverse relationship from the target to the source exists in a logical sense, but is not typically represented explicitly in the target resource. For external references, navigating these reverse relationships requires some external infrastructure to track the relationship between resources (the REST application program interface (API) provides one such infrastructure by providing the ability to search the reverse relationship by naming search parameters for the references and by providing support for reverse includes).

Because resources are processed independently, relationships are not considered to be transitive. For example, if a Procedure resource references a Patient as its subject, and has a Procedure resource as its reason, there is no automatic rule or implication that the condition has the same patient for its subject. Instead, the subject of the condition must be established directly in the Condition resource itself. Another way to state this is that the context of the subject is not “inherited”, nor does it “conduct” along the relationship to condition. The only exception to this is the case of contained resources. Note that in practice, the relationships need to describe a logical and coherent record, and in the case of the Condition and Procedure described here, they would usually be required to have the same patient for their subjects. Profiles and/or implementation guides may make rules about this.

This specification describes the use of references to other resources that have the same Fast Healthcare Interoperability Resources (FHIR) version as the source of the reference. Expected behavior for references across FHIR versions is presently undefined. References are made to resource based on their identity; there are several different identities to refer to.

Resources contain two types of references to other resources:

– Resource references – general references between resources
– Canonical references – references to resources by their canonical Universal Resource Locator (URL)

Date Created

2018-09-20

Last Modified

2019-11-01

Version

4.0.1

Update Frequency

Annual

Temporal Coverage

N/A

Spatial Coverage

United States

Source

John Snow Labs; Health Level Seven International;

Source License URL

Source License Requirements

N/A

Source Citation

N/A

Keywords

FHIR, HL7, Medical Terminology, Processes Data, Processes Information, Processes Documentation, Health Information Exchange, Electronic Health Records, FHIR Smart, Smart on FHIR

Other Titles

FHIR Reference Datatype, Electronic Health Records Exchange Through FHIR

NameDescriptionTypeConstraints
Concept_NameName of the concept in the FHIR structurestringrequired : 1
Computer_Ready_NameA Computer-ready name (e.g. a token) that identifies the structure - suitable for code generation. Note that this name (and other names relevant for code generation, including element & slice names, codes etc) may collide with reserved words in the relevant target language, and code generators will need to handle this.string-
TypeThe type the structure describes.string-
Dollar_RefThe "$ref" string value contains a Uniform Resource Identifier (URI) which identifies the location of the JSON value being referenced.string-
DescriptionA free text natural language description of the structure and its use.string-
ItemsThe value of the keyword should be an object or an array of objects. If the keyword value is an object, then for the data array to be valid each item of the array should be valid according to the schema in this value.string-
Concept NameComputer Ready NameTypeDollar RefDescriptionItems
Referenceid#/definitions/stringUnique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
ReferenceextensionarrayMay be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension there is a set of requirements that SHALL be met as part of the definition of the extension.{'$ref': '#/definitions/Extension'}
Referencereference#/definitions/stringA 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.
Reference_reference#/definitions/ElementExtensions for reference
Referencetype#/definitions/uriThe 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).
Reference_type#/definitions/ElementExtensions for type
Referenceidentifier#/definitions/IdentifierAn 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
Referencedisplay#/definitions/stringPlain text narrative that identifies the resource in addition to the resource reference.
Reference_display#/definitions/ElementExtensions for display
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