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.

• dom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources
  contained.contained.empty()
• dom-1: If the resource is contained in another resource, it SHALL NOT contain any narrative
  contained.text.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
  contained.where(('#'+id in %resource.descendants().reference).not()).empty()
• obs-7: If code is the same as a component code then the value element associated with the code SHALL NOT be present
  value.empty() or component.code.where( (coding.code = %resource.code.coding.code) and (coding.system = %resource.code.coding.system)).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]
• w5: clinical.diagnostics

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() | (children().count() > id.count())

• rim: n/a

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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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() | (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 in formation is added later.

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

• 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() | (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() | (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() | (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() | (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() | (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() | (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() | (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() | (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() | (children().count() > id.count())

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - see see identifier pattern at http://wiki.hl7.org/index.php?title=Common_Design_Patterns#Identifier_Pattern for relevant discussion. 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
• 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
• w5: id

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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 the appropriate identifier for a particular context of use to be selected from among a set of identifiers.

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.

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

• rim: n/a
• v2: N/A
• rim: Role.code or implied by context

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

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.

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

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• v2: CX.5
• rim: Role.code or implied by context

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.

see http://en.wikipedia.org/wiki/Uniform_resource_identifier

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

• rim: n/a
• v2: CX.4 / EI-2-4
• rim: II.root or Role.id.root
• servd: ./IdentifierType

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.

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

• rim: n/a
• v2: CX.1 / EI.1
• rim: II.extension or II.root if system indicates OID or GUID (Or Role.id.extension or root)
• servd: ./Value

This is not a duration - that's a measure of time (a separate type), but a duration that occurs at a fixed value of time. A Period specifies a range of time; the context of use will specify whether the entire range applies (e.g. "the patient was an inpatient of the hospital for this time range") or one value from the range applies (e.g. "give to the patient between these two times"). If duration is required, specify the type as Interval|Duration.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (children().count() > id.count())
• per-1: If present, start SHALL have a lower value than end
  start.empty() or end.empty() or (start <= end)

• rim: n/a
• v2: DR
• rim: IVL<TS>[lowClosed="true" and highClosed="true"] or URG<TS>[lowClosed="true" and highClosed="true"]
• v2: CX.7 + CX.8
• rim: Role.effectiveTime or implied by context
• servd: ./StartDate and ./EndDate

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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 %resource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• v2: CX.4 / (CX.4,CX.9,CX.10)
• rim: II.assigningAuthorityName but note that this is an improper use by the definition of the field. Also Role.scoper
• servd: ./IdentifierIssuingAuthority

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() | (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 %resource.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: .outboundRelationship[typeCode=FLFS].target

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (children().count() > id.count())
• Ref-error: 'basedOn.reference' element must point to a CarePlan resource
  startsWith('CarePlan/')

• rim: n/a
• rim: N/A
• ACSPIX2FHIR: CarePlan/${input.careplanId}

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.

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

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - see see identifier pattern at http://wiki.hl7.org/index.php?title=Common_Design_Patterns#Identifier_Pattern for relevant discussion. 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
• rim: .identifier

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.

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

• rim: n/a
• rim: N/A

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() | (children().count() > id.count())

• rim: n/a
• workflow: Event.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"
• w5: status
• ACSPIX2FHIR: final
• GREENDOT: final

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() | (children().count() > id.count())

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

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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 for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.

Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.

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

• rim: n/a
• v2: CE/CNE/CWE subset one of the sets of component 1-3 or 4-6
• rim: CV
• orim: fhir:Coding rdfs:subClassOf dt:CDCoding
• v2: C*E.1-8, C*E.10-22
• rim: union(., ./translation)
• orim: fhir:CodeableConcept.coding rdfs:subPropertyOf dt:CD.coding

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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

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

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

• rim: n/a
• v2: C*E.3
• rim: ./codeSystem
• orim: fhir:Coding.system rdfs:subPropertyOf dt:CDCoding.codeSystem
• ACSPIX2FHIR: http://roche.com/fhir/rdc/cs
• GREENDOT: http://roche.com/fhir/rdc/cs

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

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

• rim: n/a
• v2: C*E.7
• rim: ./codeSystemVersion
• orim: fhir:Coding.version rdfs:subPropertyOf dt:CDCoding.codeSystemVersion

Need to refer to a particular code in the system.

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.1
• rim: ./code
• orim: fhir:Coding.code rdfs:subPropertyOf dt:CDCoding.code
• ACSPIX2FHIR: ObservationCategoryCodes.code
• GREENDOT: clinical-observation

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

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.2 - but note this is not well followed
• rim: CV.displayName
• orim: fhir:Coding.display rdfs:subPropertyOf dt:CDCoding.displayName
• ACSPIX2FHIR: ObservationCategoryCodes.display
• GREENDOT: Clinical Observation

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

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

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

• rim: n/a
• v2: Sometimes implied by being first
• rim: CD.codingRationale
• orim: fhir:Coding.userSelected fhir:mapsTo dt:CDCoding.codingRationale. fhir:Coding.userSelected fhir:hasMap fhir:Coding.userSelected.map. fhir:Coding.userSelected.map a fhir:Map; fhir:target dt:CDCoding.codingRationale. fhir:Coding.userSelected\#true a [ fhir:source "true"; fhir:target dt:CDCoding.codingRationale\#O ]

The codes from the terminologies do not always capture the correct meaning with all the nuances of the human using them, or sometimes there is no appropriate code at all. In these cases, the text is used to capture the full meaning of the source.

Very often the text is the same as a displayName of one of the codings.

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

• rim: n/a
• v2: C*E.9. But note many systems use C*E.2 for this
• rim: ./originalText[mediaType/code="text/plain"]/data
• orim: fhir:CodeableConcept.text rdfs:subPropertyOf dt:CD.originalText

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

Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination.

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

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

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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 for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.

Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.

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

• rim: n/a
• v2: CE/CNE/CWE subset one of the sets of component 1-3 or 4-6
• rim: CV
• orim: fhir:Coding rdfs:subClassOf dt:CDCoding
• v2: C*E.1-8, C*E.10-22
• rim: union(., ./translation)
• orim: fhir:CodeableConcept.coding rdfs:subPropertyOf dt:CD.coding

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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

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

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

• rim: n/a
• v2: C*E.3
• rim: ./codeSystem
• orim: fhir:Coding.system rdfs:subPropertyOf dt:CDCoding.codeSystem
• ACSPIX2FHIR: ObservationCodes.system
• GREENDOT: http://loinc.org

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

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

• rim: n/a
• v2: C*E.7
• rim: ./codeSystemVersion
• orim: fhir:Coding.version rdfs:subPropertyOf dt:CDCoding.codeSystemVersion

Need to refer to a particular code in the system.

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.1
• rim: ./code
• orim: fhir:Coding.code rdfs:subPropertyOf dt:CDCoding.code
• ACSPIX2FHIR: ObservationCodes.code
• GREENDOT: 32016-8
• GLUCI-CHEK: BG.Evt

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

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.2 - but note this is not well followed
• rim: CV.displayName
• orim: fhir:Coding.display rdfs:subPropertyOf dt:CDCoding.displayName
• ACSPIX2FHIR: ObservationCodes.display
• GREENDOT: Glucose [Mass/volume] in Capillary blood

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

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

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

• rim: n/a
• v2: Sometimes implied by being first
• rim: CD.codingRationale
• orim: fhir:Coding.userSelected fhir:mapsTo dt:CDCoding.codingRationale. fhir:Coding.userSelected fhir:hasMap fhir:Coding.userSelected.map. fhir:Coding.userSelected.map a fhir:Map; fhir:target dt:CDCoding.codingRationale. fhir:Coding.userSelected\#true a [ fhir:source "true"; fhir:target dt:CDCoding.codingRationale\#O ]

The codes from the terminologies do not always capture the correct meaning with all the nuances of the human using them, or sometimes there is no appropriate code at all. In these cases, the text is used to capture the full meaning of the source.

Very often the text is the same as a displayName of one of the codings.

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

• rim: n/a
• v2: C*E.9. But note many systems use C*E.2 for this
• rim: ./originalText[mediaType/code="text/plain"]/data
• orim: fhir:CodeableConcept.text rdfs:subPropertyOf dt:CD.originalText

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

BG Observation -> subject element will be mapped to Patient.

Manual Entry Observation -> subject element will be mapped to Patient.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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 %resource.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
• v2: PID-3
• rim: participation[typeCode=SBJ]
• w5: who.focus

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (children().count() > id.count())
• Ref-error: 'subject.reference' element must point to a Patient resource
  startsWith('Patient/')

• rim: n/a
• rim: N/A

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.

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

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - see see identifier pattern at http://wiki.hl7.org/index.php?title=Common_Design_Patterns#Identifier_Pattern for relevant discussion. 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
• rim: .identifier

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.

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

• rim: n/a
• rim: N/A

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 or episode but still be tied to the context of the encounter or episode (e.g. pre-admission lab tests).

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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 %resource.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
• v2: PV1
• rim: inboundRelationship[typeCode=COMP].source[classCode=ENC, moodCode=EVN]
• w5: context

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.

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

• rim: n/a
• workflow: Event.occurrence[x]
• v2: OBX-14, and/or OBX-19 after v2.4 (depends on who observation made)
• rim: effectiveTime
• w5: when.done
• ACSPIX2FHIR: ${BGDate}${Timestamp}:00+02:00
• GLUCI-CHEK: BG.Dt
• GLUCI-CHEK: BG.Tm

Updated when the result is updated.

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

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

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

performer element will be mapped to Patient.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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 %resource.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
• 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]
• w5: who.actor

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (children().count() > id.count())
• Ref-error: 'performer.reference' element must point to a Patient resource
  startsWith('Patient/')

• rim: n/a
• rim: N/A

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.

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

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - see see identifier pattern at http://wiki.hl7.org/index.php?title=Common_Design_Patterns#Identifier_Pattern for relevant discussion. 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
• rim: .identifier

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.

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

• rim: n/a
• rim: N/A

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

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.

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

• rim: n/a
• workflow: Event.notDone, Event.notDoneReason (maps to valeu[x] or dataAbsentReason)
• sct-concept: < 441742003 |Evaluation finding|
• v2: OBX.2, OBX.5, OBX.6
• rim: value
• sct-attr: 363714003 |Interprets|
• ACSPIX2FHIR: delete obs.valueQuantity

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

Precision is handled implicitly in almost all cases of measurement.

The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).

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

• rim: n/a
• v2: SN.2 / CQ - N/A
• rim: PQ.value, CO.value, MO.value, IVL.high or IVL.low depending on the value
• ACSPIX2FHIR: BG.Val
• GREENDOT: com.roche.greendot.engine.finalValueDetected.getMeasurement().getValue()
• GLUCI-CHEK: BG.Val

Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.

This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.

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

• rim: n/a
• v2: SN.1 / CQ.1
• rim: IVL properties

There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: (see OBX.6 etc.) / CQ.2
• rim: PQ.unit
• ACSPIX2FHIR: ${deviceBGUnit}
• GREENDOT: type of metric

Need to know the system that defines the coded form of the unit.

see http://en.wikipedia.org/wiki/Uniform_resource_identifier

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

• rim: n/a
• v2: (see OBX.6 etc.) / CQ.2
• rim: CO.codeSystem, PQ.translation.codeSystem
• ACSPIX2FHIR: http://unitsofmeasure.org
• GREENDOT: http://unitsofmeasure.org

Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.

The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.

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

• rim: n/a
• v2: (see OBX.6 etc.) / CQ.2
• rim: PQ.code, MO.currency, PQ.translation.code
• ACSPIX2FHIR: ${deviceBGUnit}
• GREENDOT: type of metric display

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() | (children().count() > id.count())

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• workflow: Event.notDone, Event.notDoneReason (maps to valeu[x] or dataAbsentReason)
• v2: N/A
• rim: value.nullFlavor

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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 for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.

Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.

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

• rim: n/a
• v2: CE/CNE/CWE subset one of the sets of component 1-3 or 4-6
• rim: CV
• orim: fhir:Coding rdfs:subClassOf dt:CDCoding
• v2: C*E.1-8, C*E.10-22
• rim: union(., ./translation)
• orim: fhir:CodeableConcept.coding rdfs:subPropertyOf dt:CD.coding

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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

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

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

• rim: n/a
• v2: C*E.3
• rim: ./codeSystem
• orim: fhir:Coding.system rdfs:subPropertyOf dt:CDCoding.codeSystem
• ACSPIX2FHIR: input.Val="HI" then 'http://hl7.org/fhir/v3/nullFlavor' elseIf "LO" then 'http://hl7.org/fhir/v3/nullFlavor' elseIf "-" then 'http://hl7.org/fhir/data-absent-reason'
• GREENDOT: input.Val="HI" then 'http://hl7.org/fhir/v3/nullFlavor' elseIf "LO" then 'http://hl7.org/fhir/v3/nullFlavor' elseIf "-" then 'http://hl7.org/fhir/data-absent-reason'

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

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

• rim: n/a
• v2: C*E.7
• rim: ./codeSystemVersion
• orim: fhir:Coding.version rdfs:subPropertyOf dt:CDCoding.codeSystemVersion

Need to refer to a particular code in the system.

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.1
• rim: ./code
• orim: fhir:Coding.code rdfs:subPropertyOf dt:CDCoding.code
• ACSPIX2FHIR: input.Val="HI" then 'PINF' elseIf "LO" then 'NINF' elseIf "-" then 'unknown'
• GREENDOT: input.Val="HI" then 'PINF' elseIf "LO" then 'NINF' elseIf "-" then 'unknown'
• GLUCI-CHEK: BG.Val

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

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.2 - but note this is not well followed
• rim: CV.displayName
• orim: fhir:Coding.display rdfs:subPropertyOf dt:CDCoding.displayName
• ACSPIX2FHIR: input.Val="HI" then 'positive infinity' elseIf "LO" then 'negative infinity' elseIf "-" then 'Unknown'
• GREENDOT: input.Val="HI" then 'positive infinity' elseIf "LO" then 'negative infinity' elseIf "-" then 'Unknown'

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

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

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

• rim: n/a
• v2: Sometimes implied by being first
• rim: CD.codingRationale
• orim: fhir:Coding.userSelected fhir:mapsTo dt:CDCoding.codingRationale. fhir:Coding.userSelected fhir:hasMap fhir:Coding.userSelected.map. fhir:Coding.userSelected.map a fhir:Map; fhir:target dt:CDCoding.codingRationale. fhir:Coding.userSelected\#true a [ fhir:source "true"; fhir:target dt:CDCoding.codingRationale\#O ]

The codes from the terminologies do not always capture the correct meaning with all the nuances of the human using them, or sometimes there is no appropriate code at all. In these cases, the text is used to capture the full meaning of the source.

Very often the text is the same as a displayName of one of the codings.

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

• rim: n/a
• v2: C*E.9. But note many systems use C*E.2 for this
• rim: ./originalText[mediaType/code="text/plain"]/data
• orim: fhir:CodeableConcept.text rdfs:subPropertyOf dt:CD.originalText
• ACSPIX2FHIR: 'Above sensor range' : 'Below sensor range'
• GREENDOT: 'Above sensor range' : 'Below sensor range'

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

Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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|

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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 for translations and alternate encodings within a code system. Also supports communication of the same instance to systems requiring different encodings.

Codes may be defined very casually in enumerations, or code lists, up to very formal definitions such as SNOMED CT - see the HL7 v3 Core Principles for more information. Ordering of codings is undefined and SHALL NOT be used to infer meaning. Generally, at most only one of the coding values will be labeled as UserSelected = true.

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

• rim: n/a
• v2: CE/CNE/CWE subset one of the sets of component 1-3 or 4-6
• rim: CV
• orim: fhir:Coding rdfs:subClassOf dt:CDCoding
• v2: C*E.1-8, C*E.10-22
• rim: union(., ./translation)
• orim: fhir:CodeableConcept.coding rdfs:subPropertyOf dt:CD.coding

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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

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

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

• rim: n/a
• v2: C*E.3
• rim: ./codeSystem
• orim: fhir:Coding.system rdfs:subPropertyOf dt:CDCoding.codeSystem
• ACSPIX2FHIR: http://hl7.org/fhir/v2/0078

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

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

• rim: n/a
• v2: C*E.7
• rim: ./codeSystemVersion
• orim: fhir:Coding.version rdfs:subPropertyOf dt:CDCoding.codeSystemVersion

Need to refer to a particular code in the system.

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.1
• rim: ./code
• orim: fhir:Coding.code rdfs:subPropertyOf dt:CDCoding.code
• ACSPIX2FHIR: 'L' or 'H'

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

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: C*E.2 - but note this is not well followed
• rim: CV.displayName
• orim: fhir:Coding.display rdfs:subPropertyOf dt:CDCoding.displayName

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

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

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

• rim: n/a
• v2: Sometimes implied by being first
• rim: CD.codingRationale
• orim: fhir:Coding.userSelected fhir:mapsTo dt:CDCoding.codingRationale. fhir:Coding.userSelected fhir:hasMap fhir:Coding.userSelected.map. fhir:Coding.userSelected.map a fhir:Map; fhir:target dt:CDCoding.codingRationale. fhir:Coding.userSelected\#true a [ fhir:source "true"; fhir:target dt:CDCoding.codingRationale\#O ]

The codes from the terminologies do not always capture the correct meaning with all the nuances of the human using them, or sometimes there is no appropriate code at all. In these cases, the text is used to capture the full meaning of the source.

Very often the text is the same as a displayName of one of the codings.

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

• rim: n/a
• v2: C*E.9. But note many systems use C*E.2 for this
• rim: ./originalText[mediaType/code="text/plain"]/data
• orim: fhir:CodeableConcept.text rdfs:subPropertyOf dt:CD.originalText

Need to be able to provide free text additional information.

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• workflow: Event.note
• 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 body-site-instance.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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() | (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() | (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 %resource.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|

BG Observation -> device element will be mapped to DeviceMetric

Manual Entry Observation -> device element will be mapped to DeviceMetric

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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 %resource.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|
• GLUCI-CHEK: BG.D

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (children().count() > id.count())
• Ref-error: 'device.reference' element must point to a Device resource
  startsWith('DeviceMetric/')

• rim: n/a
• rim: N/A
• ACSPIX2FHIR: DeviceMetric/${input.deviceMetricId}
• GREENDOT: DeviceMetric/${DeviceMetricId}

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.

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

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - see see identifier pattern at http://wiki.hl7.org/index.php?title=Common_Design_Patterns#Identifier_Pattern for relevant discussion. 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
• rim: .identifier

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.

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

• rim: n/a
• rim: N/A

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 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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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]

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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() | (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() | (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() | (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() | (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() | (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() | (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

Note that FHIR strings may not exceed 1MB in size

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

• rim: n/a
• v2: OBX-7
• rim: value:ST

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.

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

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

• rim: n/a
• v2: Relationships established by OBX-4 usage
• rim: outBoundRelationship

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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() | (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

A relationship type SHOULD be provided.

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

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

• rim: n/a
• v2: N/A
• rim: .typeCode
• ACSPIX2FHIR: has-member

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() | (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 %resource.contained.id.trace('ids'))

• rim: n/a
• rim: The target of a resource reference is a RIM entry point (Act, Role, or Entity)
• rim: .targetObservation

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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

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.

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (children().count() > id.count())
• Ref-error: 'related.target.reference' element must point to an Observation resource
  startsWith('Observation/')

• rim: n/a
• rim: N/A
• ACSPIX2FHIR: Observation/${relatedObservationId}
• GLUCI-CHEK: BG.Evt
• GLUCI-CHEK: BG.Ctrl
• GLUCI-CHEK: BG.Evt
• GLUCI-CHEK: BG.Evt
• GLUCI-CHEK: BG.Evt
• GLUCI-CHEK: BG.Evt
• GLUCI-CHEK: BG.Evt

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.

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

• rim: n/a
• v2: CX / EI (occasionally, more often EI maps to a resource id or a URL)
• rim: II - see see identifier pattern at http://wiki.hl7.org/index.php?title=Common_Design_Patterns#Identifier_Pattern for relevant discussion. 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
• rim: .identifier

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.

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

• rim: n/a
• rim: N/A

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.

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

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

• rim: n/a
• v2: containment by OBX-4?
• rim: outBoundRelationship[typeCode=COMP]

Note that FHIR strings may not exceed 1MB in size

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

• 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() | (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() | (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

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

Not all terminology uses fit this general pattern. In some cases, models should not use CodeableConcept and use Coding directly and provide their own structure for managing text, codings, translations and the relationship between elements and pre- and post-coordination.

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

• rim: n/a
• v2: CE/CNE/CWE
• rim: CD
• orim: fhir:CodeableConcept rdfs:subClassOf dt:CD
• sct-concept: < 363787002 |Observable entity| OR < 386053000 |Evaluation procedure|
• v2: OBX-3
• rim: code
• w5: what

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

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).

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

• rim: n/a
• sct-concept: 363714003 |Interprets| < 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 "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.

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

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

• ele-1: All FHIR elements must have a @value or children
  hasValue() | (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|

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 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.

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