Measurements and simple assertions made about a patient, device or other subject.

Used for simple observations such as device measurements, laboratory atomic results, vital signs, height, weight, smoking status, comments, etc. Other resources are used to provide context for observations such as lab reports, etc.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content.

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.

This element is labelled as a modifier because the implicit rules may provide additional knowledge about the resource that modifies it's meaning or interpretation.

An Extension

R4B: Observation.effective[x] additional types (Period, Timing, instant)

Element Observation.effective[x] is mapped to FHIR STU3 element Observation.effective[x] as SourceIsBroaderThanTarget. The mappings for Observation.effective[x] do not cover the following types: instant, Period, Timing. The target context Observation.effective[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation. At least a date should be present unless this observation is a historical report. For recording imprecise or "fuzzy" times (For example, a blood glucose measurement taken "after breakfast") use the Timing datatype which allow the measurement to be tied to regular life events.

R4B: Observation.value[x] additional types (integer, Range, Ratio, SampledData, Period)

Element Observation.value[x] is mapped to FHIR STU3 element Observation.value[x] as SourceIsBroaderThanTarget. The mappings for Observation.value[x] do not cover the following types: integer, Period, Range, Ratio, SampledData. The target context Observation.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation. An observation may have; 1) a single value here, 2) both a value and a set of related or component values, or 3) only a set of related or component values. If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For additional guidance, see the Notes section below.

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. Usually modifier elements provide negation or qualification. In order 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.

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.

The status of the result value.

This element is labeled as a modifier because the status contains codes that mark the resource as not currently valid.

Codes providing the status of an observation.

Need to track the status of individual results. Some results are finalized before the whole report is finalized.

Describes what was observed. Sometimes this is called the observation "name".

Codes identifying names of simple observations.

Knowing what kind of observation is being made is essential to understanding the observation.

R4B: Observation.meta additional types (Meta) additional types from child elements (lastUpdated, profile, security, source, tag, versionId)

Element Observation.meta is mapped to FHIR STU3 element Observation.meta as SourceIsBroaderThanTarget. The mappings for Observation.meta do not cover the following types: Meta. The mappings for Observation.meta do not cover the following types based on type expansion: lastUpdated, profile, security, source, tag, versionId.

R4B: Observation.text additional types (Narrative) additional types from child elements (div, status)

Element Observation.text is mapped to FHIR STU3 element Observation.text as SourceIsBroaderThanTarget. The mappings for Observation.text do not cover the following types: Narrative. The mappings for Observation.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. 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.

R4B: Observation.effective[x] additional types (Period, Timing, instant)

Element Observation.effective[x] is mapped to FHIR STU3 element Observation.effective[x] as SourceIsBroaderThanTarget. The mappings for Observation.effective[x] do not cover the following types: instant, Period, Timing. The target context Observation.effective[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation. At least a date should be present unless this observation is a historical report. For recording imprecise or "fuzzy" times (For example, a blood glucose measurement taken "after breakfast") use the Timing datatype which allow the measurement to be tied to regular life events.

R4B: Observation.value[x] additional types (integer, Range, Ratio, SampledData, Period)

Element Observation.value[x] is mapped to FHIR STU3 element Observation.value[x] as SourceIsBroaderThanTarget. The mappings for Observation.value[x] do not cover the following types: integer, Period, Range, Ratio, SampledData. The target context Observation.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation. An observation may have; 1) a single value here, 2) both a value and a set of related or component values, or 3) only a set of related or component values. If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For additional guidance, see the Notes section below.

R4B: Observation.identifier additional types (Identifier) additional types from child elements (assigner, period, system, type, use, value)

Element Observation.identifier is mapped to FHIR STU3 element Observation.identifier as SourceIsBroaderThanTarget. The mappings for Observation.identifier do not cover the following types: Identifier. The mappings for Observation.identifier do not cover the following types based on type expansion: assigner, period, system, type, use, value.

R4B: Observation.basedOn

Element Observation.basedOn is mapped to FHIR STU3 element Observation.basedOn as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.basedOn with unmapped reference targets: CarePlan, DeviceRequest, ImmunizationRecommendation, MedicationRequest, NutritionOrder, ServiceRequest.

R4B: Observation.subject

Element Observation.subject is mapped to FHIR STU3 element Observation.subject as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.subject with unmapped reference targets: Device, Group, Location, Medication, Organization, Patient, Practitioner, Procedure, Substance. One would expect this element to be a cardinality of 1..1. The only circumstance in which the subject can be missing is when the observation is made by a device that does not know the patient. In this case, the observation SHALL be matched to a patient through some context/channel matching technique, and at this point, the observation should be updated.

R4B: Observation.encounter additional types from child elements (display, identifier, reference, type)

Element Observation.encounter is mapped to FHIR STU3 element Observation.context as SourceIsBroaderThanTarget. The mappings for Observation.encounter do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.encounter with unmapped reference targets: Encounter. This will typically be the encounter the event occurred within, 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 laboratory tests).

R4B: Observation.performer

Element Observation.performer is mapped to FHIR STU3 element Observation.performer as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.performer with unmapped reference targets: CareTeam, Organization, Patient, Practitioner, PractitionerRole, RelatedPerson.

R4B: Observation.note additional types (Annotation) additional types from child elements (time)

Element Observation.note is mapped to FHIR STU3 element Observation.comment as SourceIsBroaderThanTarget. The mappings for Observation.note do not cover the following types: Annotation. The mappings for Observation.note do not cover the following types based on type expansion: time. May include general statements about the observation, or statements about significant, unexpected or unreliable results values, or information about its source when relevant to its interpretation.

R4B: Observation.specimen additional types from child elements (display, identifier, reference, type)

Element Observation.specimen is mapped to FHIR STU3 element Observation.specimen as SourceIsBroaderThanTarget. The mappings for Observation.specimen do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.specimen with unmapped reference targets: Specimen. Should only be used if not implicit in code found in Observation.code. Observations are not made on specimens themselves; they are made on a subject, but in many cases by the means of a specimen. Note that although specimens are often involved, they are not always tracked and reported explicitly. Also note that observation resources may be used in contexts that track the specimen explicitly (e.g. Diagnostic Report).

R4B: Observation.device additional types from child elements (display, identifier, reference, type)

Element Observation.device is mapped to FHIR STU3 element Observation.device as SourceIsBroaderThanTarget. The mappings for Observation.device do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.device with unmapped reference targets: Device, DeviceMetric. Note that this is not meant to represent a device involved in the transmission of the result, e.g., a gateway. Such devices may be documented using the Provenance resource where relevant.

R4B: Observation.referenceRange.age additional types (Range) additional types from child elements (high, low)

Element Observation.referenceRange.age is mapped to FHIR STU3 element Observation.referenceRange.age as SourceIsBroaderThanTarget. The mappings for Observation.referenceRange.age do not cover the following types: Range. The mappings for Observation.referenceRange.age do not cover the following types based on type expansion: high, low.

R4B: Observation.partOf (new:Reference(MedicationAdministration,MedicationDispense,MedicationStatement,Procedure,Immunization,ImagingStudy))

Element Observation.partOf has a context of Observation.related based on following the parent source element upwards and mapping to Observation. Element Observation.partOf has no mapping targets in FHIR STU3. Typically, this is because the element has been added (is a new element). To link an Observation to an Encounter use encounter. See the Notes below for guidance on referencing another Observation.

R4B: Observation.focus (new:Reference(Resource))

Element Observation.focus has a context of Observation.related based on following the parent source element upwards and mapping to Observation. Element Observation.focus has no mapping targets in FHIR STU3. Typically, this is because the element has been added (is a new element). Typically, an observation is made about the subject - a patient, or group of patients, location, or device - and the distinction between the subject and what is directly measured for an observation is specified in the observation code itself ( e.g., "Blood Glucose") and does not need to be represented separately using this element. Use specimen if a reference to a specimen is required. If a code is required instead of a resource use either bodysite for bodysites or the standard extension focusCode.

R4B: Observation.hasMember

Element Observation.hasMember is mapped to FHIR STU3 element Observation.related.target as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.hasMember with unmapped reference targets: MolecularSequence, Observation, QuestionnaireResponse. When using this element, an observation will typically have either a value or a set of related resources, although both may be present in some cases. For a discussion on the ways Observations can assembled in groups together, see Notes below. Note that a system may calculate results from QuestionnaireResponse into a final score and represent the score as an Observation.

R4B: Observation.derivedFrom

Element Observation.derivedFrom is mapped to FHIR STU3 element Observation.related.target as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.derivedFrom with unmapped reference targets: DocumentReference, ImagingStudy, Media, MolecularSequence, Observation, QuestionnaireResponse. All the reference choices that are listed in this element can represent clinical observations and other measurements that may be the source for a derived value. The most common reference will be another Observation. For a discussion on the ways Observations can assembled in groups together, see Notes below.

R4B: Observation.component.value[x] additional types (boolean, integer, Range, Ratio, SampledData, Period)

Element Observation.component.value[x] is mapped to FHIR STU3 element Observation.component.value[x] as SourceIsBroaderThanTarget. The mappings for Observation.component.value[x] do not cover the following types: boolean, integer, Period, Range, Ratio, SampledData. The target context Observation.component.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation.component. Used when observation has a set of component observations. An observation may have both a value (e.g. an Apgar score) and component observations (the observations from which the Apgar score was derived). If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For additional guidance, see the Notes section below.

Measurements and simple assertions made about a patient, device or other subject.

Used for simple observations such as device measurements, laboratory atomic results, vital signs, height, weight, smoking status, comments, etc. Other resources are used to provide context for observations such as lab reports, etc.

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

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

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content may 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

R4B: Observation.meta additional types (Meta) additional types from child elements (lastUpdated, profile, security, source, tag, versionId)

Element Observation.meta is mapped to FHIR STU3 element Observation.meta as SourceIsBroaderThanTarget. The mappings for Observation.meta do not cover the following types: Meta. The mappings for Observation.meta do not cover the following types based on type expansion: lastUpdated, profile, security, source, tag, versionId.

The version specific identifier, as it appears in the version portion of the URL. This values 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 value is always populated except when the resource is first being created. The server / resource manager sets this value; what a client provides is irrelevant.

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.

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.

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.

This element is labelled as a modifier because the implicit rules may provide additional knowledge about the resource that modifies it's meaning or interpretation.

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).

A human language.

A human-readable narrative that contains a summary of the resource, and may 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 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 in formation 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

R4B: Observation.text additional types (Narrative) additional types from child elements (div, status)

Element Observation.text is mapped to FHIR STU3 element Observation.text as SourceIsBroaderThanTarget. The mappings for Observation.text do not cover the following types: Narrative. The mappings for Observation.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. 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.

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 may 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, and nor can they have their own independent transaction scope.

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.

An Extension

R4B: Observation.effective[x] additional types (Period, Timing, instant)

Element Observation.effective[x] is mapped to FHIR STU3 element Observation.effective[x] as SourceIsBroaderThanTarget. The mappings for Observation.effective[x] do not cover the following types: instant, Period, Timing. The target context Observation.effective[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation. At least a date should be present unless this observation is a historical report. For recording imprecise or "fuzzy" times (For example, a blood glucose measurement taken "after breakfast") use the Timing datatype which allow the measurement to be tied to regular life events.

R4B: Observation.value[x] additional types (integer, Range, Ratio, SampledData, Period)

Element Observation.value[x] is mapped to FHIR STU3 element Observation.value[x] as SourceIsBroaderThanTarget. The mappings for Observation.value[x] do not cover the following types: integer, Period, Range, Ratio, SampledData. The target context Observation.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation. An observation may have; 1) a single value here, 2) both a value and a set of related or component values, or 3) only a set of related or component values. If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For additional guidance, see the Notes section below.

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. Usually modifier elements provide negation or qualification. In order 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.

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.

A unique identifier assigned to this observation.

Allows observations to be distinguished and referenced.

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

An Extension

R4B: Observation.identifier additional types (Identifier) additional types from child elements (assigner, period, system, type, use, value)

Element Observation.identifier is mapped to FHIR STU3 element Observation.identifier as SourceIsBroaderThanTarget. The mappings for Observation.identifier do not cover the following types: Identifier. The mappings for Observation.identifier do not cover the following types based on type expansion: assigner, period, system, type, use, value.

The purpose of this identifier.

This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one. Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.

Identifies the purpose for this identifier, if known .

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

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

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.

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

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

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

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.

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

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.

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

Organization that issued/manages the identifier.

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.

A plan, proposal or order that is fulfilled in whole or in part by this event.

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

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

An Extension

R4B: Observation.basedOn

Element Observation.basedOn is mapped to FHIR STU3 element Observation.basedOn as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.basedOn with unmapped reference targets: CarePlan, DeviceRequest, ImmunizationRecommendation, MedicationRequest, NutritionOrder, ServiceRequest.

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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

The status of the result value.

This element is labeled as a modifier because the status contains codes that mark the resource as not currently valid.

Codes providing the status of an observation.

Need to track the status of individual results. Some results are finalized before the whole report is finalized.

A code that classifies the general type of observation being made.

In addition to the required category valueset, this element allows various categorization schemes based on the owner’s definition of the category and effectively multiple categories can be used at once. The level of granularity is defined by the category concepts in the value set.

Codes for high level observation categories.

Used for filtering what observations are retrieved and displayed.

Describes what was observed. Sometimes this is called the observation "name".

Codes identifying names of simple observations.

Knowing what kind of observation is being made is essential to understanding the observation.

The patient, or group of patients, location, or device whose characteristics (direct or indirect) are described by the observation and into whose record the observation is placed. Comments: Indirect characteristics may be those of a specimen, fetus, donor, other observer (for example a relative or EMT), or any observation made about the subject.

One would expect this element to be a cardinality of 1..1. The only circumstance in which the subject can be missing is when the observation is made by a device that does not know the patient. In this case, the observation SHALL be matched to a patient through some context/channel matching technique, and at this point, the observation should be updated.

If the target of the observation is different than the subject, the general extension observation-focal-subject. may be used. However, the distinction between the patient's own value for an observation versus that of the fetus, or the donor or blood product unit, etc., are often specified in the observation code.

Observations have no value if you don't know who or what they're about.

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

An Extension

R4B: Observation.subject

Element Observation.subject is mapped to FHIR STU3 element Observation.subject as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.subject with unmapped reference targets: Device, Group, Location, Medication, Organization, Patient, Practitioner, Procedure, Substance. One would expect this element to be a cardinality of 1..1. The only circumstance in which the subject can be missing is when the observation is made by a device that does not know the patient. In this case, the observation SHALL be matched to a patient through some context/channel matching technique, and at this point, the observation should be updated.

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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

The healthcare event (e.g. a patient and healthcare provider interaction) during which this observation is made.

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

For some observations it may be important to know the link between an observation and a particular encounter.

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

An Extension

R4B: Observation.encounter additional types from child elements (display, identifier, reference, type)

Element Observation.encounter is mapped to FHIR STU3 element Observation.context as SourceIsBroaderThanTarget. The mappings for Observation.encounter do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.encounter with unmapped reference targets: Encounter. This will typically be the encounter the event occurred within, 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 laboratory tests).

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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

The time or time-period the observed value is asserted as being true. For biological subjects - e.g. human patients - this is usually called the "physiologically relevant time". This is usually either the time of the procedure or of specimen collection, but very often the source of the date/time is not known, only the date/time itself.

At least a date should be present unless this observation is a historical report.

Knowing when an observation was deemed true is important to its relevance as well as determining trends.

The date and time this observation was made available to providers, typically after the results have been reviewed and verified.

Updated when the result is updated.

Who was responsible for asserting the observed value as "true".

May give a degree of confidence in the observation and also indicates where follow-up questions should be directed.

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

An Extension

R4B: Observation.performer

Element Observation.performer is mapped to FHIR STU3 element Observation.performer as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.performer with unmapped reference targets: CareTeam, Organization, Patient, Practitioner, PractitionerRole, 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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

The information determined as a result of making the observation, if the information has a simple value.

Normally, an observation will have either a single value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. This element has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueString, valueBoolean, valueRange, valueRatio, valueSampledData, valueAttachment, valueTime, valueDateTime, or valuePeriod. (The name format is "'value' + the type name" with a capital on the first letter of the type).

If the data element is usually coded or if the type associated with the Observation.value defines a coded value, use CodeableConcept instead of string datatype even if the value is uncoded text. A value set is bound to the ValueCodeableConcept element. For further discussion and examples see the notes section below.

An observation exists to have a value, though it may not if it is in error, or if it represents a group of observations.

Provides a reason why the expected value in the element Observation.value[x] is missing.

Null or exceptional values can be represented two ways in FHIR Observations. One way is to simply include them in the value set and represent the exceptions in the value. For example, measurement values for a serology test could be "detected", "not detected", "inconclusive", or "specimen unsatisfactory". The alternate way is to use the value element for actual observations and use the explicit dataAbsentReason element to record exceptional values. For example, the dataAbsentReason code "error" could be used when the measurement was not completed. Note that an observation may only be reported if there are values to report. For example differential cell counts values may be reported only when > 0. Because of these options, use-case agreements are required to interpret general observations for null or exceptional values.

Codes specifying why the result (Observation.value[x]) is missing.

For many results it is necessary to handle exceptional values in measurements.

The assessment made based on the result of the observation. Intended as a simple compact code often placed adjacent to the result value in reports and flow sheets to signal the meaning/normalcy status of the result. Otherwise known as abnormal flag.

Unless not suitable, these codes SHALL be taken from Observation Interpretation Codes
(extensible to http://hl7.org/fhir/ValueSet/observation-interpretation|3.0.2)

Codes identifying interpretations of observations.

For some results, particularly numeric results, an interpretation is necessary to fully understand the significance of a result.

May include statements about significant, unexpected or unreliable values, or information about the source of the value where this may be relevant to the interpretation of the result.

Need to be able to provide free text additional information.

unique id for the element within a resource (for internal references)

An Extension

R4B: Observation.note additional types (Annotation) additional types from child elements (time)

Element Observation.note is mapped to FHIR STU3 element Observation.comment as SourceIsBroaderThanTarget. The mappings for Observation.note do not cover the following types: Annotation. The mappings for Observation.note do not cover the following types based on type expansion: time. May include general statements about the observation, or statements about significant, unexpected or unreliable results values, or information about its source when relevant to its interpretation.

The actual value

Indicates the site on the subject's body where the observation was made (i.e. the target site).

Only used if not implicit in code found in Observation.code. In many systems, this may be represented as a related observation instead of an inline component. If the use case requires BodySite to be handled as a separate resource (e.g. to identify and track separately) then use the standard extension body-site-instance.

Codes describing anatomical locations. May include laterality.

Indicates the mechanism used to perform the observation.

Only used if not implicit in code for Observation.code.

Methods for simple observations.

In some cases, method can impact results and is thus used for determining whether results can be compared or determining significance of results.

The specimen that was used when this observation was made.

Should only be used if not implicit in code found in Observation.code. Observations are not made on specimens themselves; they are made on a subject, but in many cases by the means of a specimen. Note that although specimens are often involved, they are not always tracked and reported explicitly. Also note that observation resources may be used in contexts that track the specimen explicitly (e.g. Diagnostic Report).

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

An Extension

R4B: Observation.specimen additional types from child elements (display, identifier, reference, type)

Element Observation.specimen is mapped to FHIR STU3 element Observation.specimen as SourceIsBroaderThanTarget. The mappings for Observation.specimen do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.specimen with unmapped reference targets: Specimen. Should only be used if not implicit in code found in Observation.code. Observations are not made on specimens themselves; they are made on a subject, but in many cases by the means of a specimen. Note that although specimens are often involved, they are not always tracked and reported explicitly. Also note that observation resources may be used in contexts that track the specimen explicitly (e.g. Diagnostic Report).

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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

The device used to generate the observation data.

An extension should be used if further typing of the device is needed. Devices used to support obtaining an observation can be represented using either an extension or through the Observation.related element.

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

An Extension

R4B: Observation.device additional types from child elements (display, identifier, reference, type)

Element Observation.device is mapped to FHIR STU3 element Observation.device as SourceIsBroaderThanTarget. The mappings for Observation.device do not cover the following types based on type expansion: display, identifier, reference, type. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.device with unmapped reference targets: Device, DeviceMetric. Note that this is not meant to represent a device involved in the transmission of the result, e.g., a gateway. Such devices may be documented using the Provenance resource where relevant.

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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

Guidance on how to interpret the value by comparison to a normal or recommended range.

Most observations only have one generic reference range. Systems MAY choose to restrict to only supplying the relevant reference range based on knowledge about the patient (e.g., specific to the patient's age, gender, weight and other factors), but this may not be possible or appropriate. Whenever more than one reference range is supplied, the differences between them SHOULD be provided in the reference range and/or age properties.

Knowing what values are considered "normal" can help evaluate the significance of a particular result. Need to be able to provide multiple reference ranges for different contexts.

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. In order 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.

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 that contains it. Usually modifier elements provide negation or qualification. In order 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.

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.

The value of the low bound of the reference range. The low bound of the reference range endpoint is inclusive of the value (e.g. reference range is >=5 - <=9). If the low bound is omitted, it is assumed to be meaningless (e.g. reference range is <=2.3).

The value of the high bound of the reference range. The high bound of the reference range endpoint is inclusive of the value (e.g. reference range is >=5 - <=9). If the high bound is omitted, it is assumed to be meaningless (e.g. reference range is >= 2.3).

Codes to indicate the what part of the targeted reference population it applies to. For example, the normal or therapeutic range.

This SHOULD be populated if there is more than one range. If this element is not present then the normal range is assumed.

Code for the meaning of a reference range.

Need to be able to say what kind of reference range this is - normal, recommended, therapeutic, etc, - for proper interpretation.

Codes to indicate the target population this reference range applies to. For example, a reference range may be based on the normal population or a particular sex or race.

This SHOULD be populated if there is more than one range. If this element is not present then the normal population is assumed.

Codes identifying the population the reference range applies to.

Need to be able to identify the target population for proper interpretation.

The age at which this reference range is applicable. This is a neonatal age (e.g. number of weeks at term) if the meaning says so.

Some analytes vary greatly over age.

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

An Extension

R4B: Observation.referenceRange.age additional types (Range) additional types from child elements (high, low)

Element Observation.referenceRange.age is mapped to FHIR STU3 element Observation.referenceRange.age as SourceIsBroaderThanTarget. The mappings for Observation.referenceRange.age do not cover the following types: Range. The mappings for Observation.referenceRange.age do not cover the following types based on type expansion: high, low.

The low limit. The boundary is inclusive.

If the low element is missing, the low boundary is not known.

The high limit. The boundary is inclusive.

If the high element is missing, the high boundary is not known.

Text based reference range in an observation which may be used when a quantitative range is not appropriate for an observation. An example would be a reference value of "Negative" or a list or table of 'normals'.

A reference to another resource (usually another Observation) whose relationship is defined by the relationship type code.

For a discussion on the ways Observations can assembled in groups together see Notes below.

Normally, an observation will have either a value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and a set of related observations or sometimes a QuestionnaireResponse from which the measure is derived.

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

An Extension

R4B: Observation.partOf (new:Reference(MedicationAdministration,MedicationDispense,MedicationStatement,Procedure,Immunization,ImagingStudy))

Element Observation.partOf has a context of Observation.related based on following the parent source element upwards and mapping to Observation. Element Observation.partOf has no mapping targets in FHIR STU3. Typically, this is because the element has been added (is a new element). To link an Observation to an Encounter use encounter. See the Notes below for guidance on referencing another Observation.

R4B: Observation.focus (new:Reference(Resource))

Element Observation.focus has a context of Observation.related based on following the parent source element upwards and mapping to Observation. Element Observation.focus has no mapping targets in FHIR STU3. Typically, this is because the element has been added (is a new element). Typically, an observation is made about the subject - a patient, or group of patients, location, or device - and the distinction between the subject and what is directly measured for an observation is specified in the observation code itself ( e.g., "Blood Glucose") and does not need to be represented separately using this element. Use specimen if a reference to a specimen is required. If a code is required instead of a resource use either bodysite for bodysites or the standard extension focusCode.

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 that contains it. Usually modifier elements provide negation or qualification. In order 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.

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.

A code specifying the kind of relationship that exists with the target resource.

The "derived-from" type is the only logical choice when referencing the QuestionnaireAnswer resource.

Codes specifying how two observations are related.

A relationship type SHOULD be provided.

A reference to the observation or QuestionnaireResponse resource that is related to this observation.

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

An Extension

R4B: Observation.hasMember

Element Observation.hasMember is mapped to FHIR STU3 element Observation.related.target as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.hasMember with unmapped reference targets: MolecularSequence, Observation, QuestionnaireResponse. When using this element, an observation will typically have either a value or a set of related resources, although both may be present in some cases. For a discussion on the ways Observations can assembled in groups together, see Notes below. Note that a system may calculate results from QuestionnaireResponse into a final score and represent the score as an Observation.

R4B: Observation.derivedFrom

Element Observation.derivedFrom is mapped to FHIR STU3 element Observation.related.target as RelatedTo. The standard extension alternate-reference has been mapped as the representation of FHIR R4B element Observation.derivedFrom with unmapped reference targets: DocumentReference, ImagingStudy, Media, MolecularSequence, Observation, QuestionnaireResponse. All the reference choices that are listed in this element can represent clinical observations and other measurements that may be the source for a derived value. The most common reference will be another Observation. For a discussion on the ways Observations can assembled in groups together, see Notes below.

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.

An identifier for the other resource. This is used when there is no way to reference the other resource directly, either because the entity 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.

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.

Some observations have multiple component observations. These component observations are expressed as separate code value pairs that share the same attributes. Examples include systolic and diastolic component observations for blood pressure measurement and multiple component observations for genetics observations.

For a discussion on the ways Observations can be assembled in groups together see Notes below.

Component observations share the same attributes in the Observation resource as the primary observation and are always treated a part of a single observation (they are not separable). However, the reference range for the primary observation value is not inherited by the component values and is required when appropriate for each component observation.

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

An Extension

R4B: Observation.component.value[x] additional types (boolean, integer, Range, Ratio, SampledData, Period)

Element Observation.component.value[x] is mapped to FHIR STU3 element Observation.component.value[x] as SourceIsBroaderThanTarget. The mappings for Observation.component.value[x] do not cover the following types: boolean, integer, Period, Range, Ratio, SampledData. The target context Observation.component.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Observation.component. Used when observation has a set of component observations. An observation may have both a value (e.g. an Apgar score) and component observations (the observations from which the Apgar score was derived). If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For additional guidance, see the Notes section below.

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 that contains it. Usually modifier elements provide negation or qualification. In order 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.

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.

Describes what was observed. Sometimes this is called the observation "code".

Codes identifying names of simple observations.

Knowing what kind of observation is being made is essential to understanding the observation.

The information determined as a result of making the observation, if the information has a simple value.

Normally, an observation will have either a single value or a set of related observations. A few observations (e.g. Apgar score) may have both a value and related observations (for an Apgar score, the observations from which the measure is derived). If a value is present, the datatype for this element should be determined by Observation.code. A CodeableConcept with just a text would be used instead of a string if the field was usually coded, or if the type associated with the Observation.code defines a coded value. For boolean values use valueCodeableConcept and select codes from <http://hl7.org/fhir/ValueSet/v2-0136> (these "yes/no" concepts can be mapped to the display name "true/false" or other mutually exclusive terms that may be needed"). The element, Observation.value[x], has a variable name depending on the type as follows: valueQuantity, valueCodeableConcept, valueRatio, valueChoice, valuePeriod, valueSampleData, or valueString (the name format is "'value' + the type name" with a capital on the first letter of the type).

An observation exists to have a value, though it may not if it is in error, or if it represents a group of observations.

Provides a reason why the expected value in the element Observation.value[x] is missing.

"Null" or exceptional values can be represented two ways in FHIR Observations. One way is to simply include them in the value set and represent the exceptions in the value. For example, measurement values for a serology test could be "detected", "not detected", "inconclusive", or "test not done". The alternate way is to use the value element for actual observations and use the explicit dataAbsentReason element to record exceptional values. For example, the dataAbsentReason code "error" could be used when the measurement was not completed. Because of these options, use-case agreements are required to interpret general observations for exceptional values.

Codes specifying why the result (Observation.value[x]) is missing.

For many results it is necessary to handle exceptional values in measurements.

The assessment made based on the result of the observation. Intended as a simple compact code often placed adjacent to the result value in reports and flow sheets to signal the meaning/normalcy status of the result. Otherwise known as abnormal flag.

The component interpretation applies only to the individual component value. For an overall interpretation all components together use thes Observation.interpretation element.

Unless not suitable, these codes SHALL be taken from Observation Interpretation Codes
(extensible to http://hl7.org/fhir/ValueSet/observation-interpretation|3.0.2)

Codes identifying interpretations of observations.

For some results, particularly numeric results, an interpretation is necessary to fully understand the significance of a result.

Guidance on how to interpret the value by comparison to a normal or recommended range.

Most observations only have one generic reference range. Systems MAY choose to restrict to only supplying the relevant reference range based on knowledge about the patient (e.g., specific to the patient's age, gender, weight and other factors), but this may not be possible or appropriate. Whenever more than one reference range is supplied, the differences between them SHOULD be provided in the reference range and/or age properties.

Knowing what values are considered "normal" can help evaluate the significance of a particular result. Need to be able to provide multiple reference ranges for different contexts.