StructureDefinition UKCore-Observation

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 laboratory reports, etc.

• dom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources
  contained.contained.empty()
• dom-4: If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated
  contained.meta.versionId.empty() and contained.meta.lastUpdated.empty()
• dom-3: If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource
  contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty()
• dom-6: A resource should have narrative for robust management
  text.`div`.exists()
• dom-5: If a resource is contained in another resource, it SHALL NOT have a security label
  contained.meta.security.empty()
• obs-7: If Observation.code is the same as an Observation.component.code then the value element associated with the code SHALL NOT be present
  value.empty() or component.code.where(coding.intersect(%resource.code.coding).exists()).empty()
• obs-6: dataAbsentReason SHALL only be present if Observation.value[x] is not present
  dataAbsentReason.empty() or value.empty()

• rim: Entity. Role, or Act
• workflow: Event
• sct-concept: < 363787002 |Observable entity|
• v2: OBX
• rim: Observation[classCode=OBS, moodCode=EVN]

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• rim: N/A

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a

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).

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• rim: N/A
• rim: Act.text?

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.

• rim: Entity. Role, or Act
• rim: N/A

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

• rim: n/a

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

• rim: n/a

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

observation

• rim: N/A

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• rim: N/A

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

• rim: n/a

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

type

• rim: N/A

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• rim: N/A

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

• rim: n/a

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

reason

• rim: N/A

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• rim: N/A

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

http://hl7.org/fhir/5.0/StructureDefinition/extension-Observation.triggeredBy

• rim: N/A

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• rim: N/A

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

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.

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

Allows observations to be distinguished and referenced.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - The Identifier class is a little looser than the v3 type II because it allows URIs as well as registered OIDs or GUIDs. Also maps to Role[classCode=IDENT]
• servd: Identifier
• workflow: Event.identifier
• w5: FiveWs.identifier
• v2: OBX.21 For OBX segments from systems without OBX-21 support a combination of ORC/OBR and OBX must be negotiated between trading partners to uniquely identify the OBX segment. Depending on how V2 has been implemented each of these may be an option: 1) OBR-3 + OBX-3 + OBX-4 or 2) OBR-3 + OBR-4 + OBX-3 + OBX-4 or 2) some other way to uniquely ID the OBR/ORC + OBX-3 + OBX-4.
• rim: id

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

References SHALL be a reference to an actual FHIR resource, and SHALL be resolveable (allowing for access control, temporary unavailability, etc.). Resolution can be either by retrieval from the URL, or, where applicable by resource type, by treating an absolute reference as a canonical URL and looking it up in a local registry/repository.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• workflow: Event.basedOn
• v2: ORC
• rim: .inboundRelationship[typeCode=COMP].source[moodCode=EVN]

To link an Observation to an Encounter use encounter. See the Notes below for guidance on referencing another Observation.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• workflow: Event.partOf
• v2: Varies by domain
• rim: .outboundRelationship[typeCode=FLFS].target

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

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• workflow: Event.status
• w5: FiveWs.status
• sct-concept: < 445584004 |Report by finality status|
• v2: OBX-11
• rim: status Amended & Final are differentiated by whether it is the subject of a ControlAct event with a type of "revise"

Used for filtering what observations are retrieved and displayed.

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• w5: FiveWs.class
• rim: .outboundRelationship[typeCode="COMP].target[classCode="LIST", moodCode="EVN"].code

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

All code-value and, if present, component.code-component.value pairs need to be taken into account to correctly understand the meaning of the observation.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• workflow: Event.code
• w5: FiveWs.what[x]
• sct-concept: < 363787002 |Observable entity| OR < 386053000 |Evaluation procedure|
• v2: OBX-3
• rim: code
• sct-attr: 116680003 |Is a|

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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• workflow: Event.subject
• w5: FiveWs.subject[x]
• v2: PID-3
• rim: participation[typeCode=RTGT]
• w5: FiveWs.subject

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• w5: FiveWs.subject[x]
• v2: OBX-3
• rim: participation[typeCode=SBJ]
• w5: FiveWs.subject

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• workflow: Event.context
• w5: FiveWs.context
• v2: PV1
• rim: inboundRelationship[typeCode=COMP].source[classCode=ENC, moodCode=EVN]

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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• workflow: Event.occurrence[x]
• w5: FiveWs.done[x]
• v2: OBX-14, and/or OBX-19 after v2.4 (depends on who observation made)
• rim: effectiveTime

For Observations that don’t require review and verification, it may be the same as the lastUpdated time of the resource itself. For Observations that do require review and verification for certain updates, it might not be the same as the lastUpdated time of the resource itself due to a non-clinically significant update that doesn’t require the new version to be reviewed and verified again.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• w5: FiveWs.recorded
• v2: OBR.22 (or MSH.7), or perhaps OBX-19 (depends on who observation made)
• rim: participation[typeCode=AUT].time

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

References SHALL be a reference to an actual FHIR resource, and SHALL be resolveable (allowing for access control, temporary unavailability, etc.). Resolution can be either by retrieval from the URL, or, where applicable by resource type, by treating an absolute reference as a canonical URL and looking it up in a local registry/repository.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• workflow: Event.performer.actor
• w5: FiveWs.actor
• v2: OBX.15 / (Practitioner) OBX-16, PRT-5:PRT-4='RO' / (Device) OBX-18 , PRT-10:PRT-4='EQUIP' / (Organization) OBX-23, PRT-8:PRT-4='PO'
• rim: participation[typeCode=PRF]

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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• sct-concept: < 441742003 |Evaluation finding|
• v2: OBX.2, OBX.5, OBX.6
• rim: value
• sct-attr: 363714003 |Interprets|

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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• v2: N/A
• rim: value.nullFlavor

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

Historically used for laboratory results (known as 'abnormal flag' ), its use extends to other use cases where coded interpretations are relevant. Often reported as one or more simple compact codes this element is often placed adjacent to the result value in reports and flow sheets to signal the meaning/normalcy status of the result.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• sct-concept: < 260245000 |Findings values|
• v2: OBX-8
• rim: interpretationCode
• sct-attr: 363713009 |Has interpretation|

Need to be able to provide free text additional information.

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: N/A
• rim: Act
• v2: NTE.3 (partner NTE to OBX, or sometimes another (child?) OBX)
• rim: subjectOf.observationEvent[code="annotation"].value

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 bodySite.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• sct-concept: < 123037004 |Body structure|
• v2: OBX-20
• rim: targetSiteCode
• sct-attr: 718497002 |Inherent location|

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

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• v2: OBX-17
• rim: methodCode

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).

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• sct-concept: < 123038009 |Specimen|
• v2: SPM segment
• rim: participation[typeCode=SPC].specimen
• sct-attr: 704319004 |Inherent in|

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ref-1: SHALL have a contained resource if a local reference is provided
  reference.startsWith('#').not() or (reference.substring(1).trace('url') in %rootResource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• sct-concept: < 49062001 |Device|
• v2: OBX-17 / PRT -10
• rim: participation[typeCode=DEV]
• sct-attr: 424226004 |Using device|

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.

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 might 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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• obs-3: Must have at least a low or a high or text
  low.exists() or high.exists() or text.exists()

• rim: n/a
• v2: OBX.7
• rim: outboundRelationship[typeCode=REFV]/target[classCode=OBS, moodCode=EVN]

• rim: n/a

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

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.

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• ext-1: Must have either extensions or value[x], not both
  extension.exists() != value.exists()

• rim: n/a
• rim: N/A

The context of use may frequently define what kind of quantity this is and therefore what kind of units can be used. The context of use may also restrict the values for the comparator.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• qty-3: If a code for the unit is present, the system SHALL also be present
  code.empty() or system.exists()
• sqty-1: The comparator is not used on a SimpleQuantity
  comparator.empty()

• rim: n/a
• v2: SN (see also Range) or CQ
• rim: PQ, IVL<PQ>, MO, CO, depending on the values
• v2: OBX-7
• rim: value:IVL_PQ.low

The context of use may frequently define what kind of quantity this is and therefore what kind of units can be used. The context of use may also restrict the values for the comparator.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• qty-3: If a code for the unit is present, the system SHALL also be present
  code.empty() or system.exists()
• sqty-1: The comparator is not used on a SimpleQuantity
  comparator.empty()

• rim: n/a
• v2: SN (see also Range) or CQ
• rim: PQ, IVL<PQ>, MO, CO, depending on the values
• v2: OBX-7
• rim: value:IVL_PQ.high

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

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• sct-concept: < 260245000 |Findings values| OR < 365860008 |General clinical state finding| OR < 250171008 |Clinical history or observation findings| OR < 415229000 |Racial group| OR < 365400002 |Finding of puberty stage| OR < 443938003 |Procedure carried out on subject|
• v2: OBX-10
• rim: interpretationCode

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

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• sct-concept: < 260245000 |Findings values| OR < 365860008 |General clinical state finding| OR < 250171008 |Clinical history or observation findings| OR < 415229000 |Racial group| OR < 365400002 |Finding of puberty stage| OR < 443938003 |Procedure carried out on subject|
• v2: OBX-10
• rim: interpretationCode

Some analytes vary greatly over age.

The stated low and high value are assumed to have arbitrarily high precision when it comes to determining which values are in the range. I.e. 1.99 is not in the range 2 -> 3.

• ele-1: All FHIR elements must have a @value or children
  hasValue() or (children().count() > id.count())
• rng-2: If present, low SHALL have a lower value than high
  low.empty() or high.empty() or (low <= high)

• rim: n/a
• v2: NR and also possibly SN (but see also quantity)
• rim: IVL<QTY[not(type="TS")]> [lowClosed="true" and highClosed="true"]or URG<QTY[not(type="TS")]>
• rim: outboundRelationship[typeCode=PRCN].targetObservationCriterion[code="age"].value