Structured Data Capture
4.0.0-ballot - STU 4 ballot International flag

This page is part of the Structured Data Capture FHIR IG (v4.0.0-ballot: STU 4 Ballot 1) based on FHIR (HL7® FHIR® Standard) R4. The current version which supersedes this version is 3.0.0. For a full list of available versions, see the Directory of published versions

Data Type Profile: SDCUsageContext - Detailed Descriptions

Page standards status: Trial-use Maturity Level: 4

Definitions for the sdc-usagecontext data type profile.

Guidance on how to interpret the contents of this table can be found here

0. UsageContext
Must Supporttrue
Invariantssdc-uc-1: If code is gender, focus, user, venue or species, value must be CodeableConcept. If code is age, value must be Range. If code is workflow, task or program, value must be CodeableConcept or Reference (code.system!='http://terminology.hl7.org/CodeSystem/usage-context-type' or (((code.code='gender' or code.code='focus' or code.code='user' or code.code='venue' or code.code='species') implies value.exists() and value is CodeableConcept) and (code.code='age' implies value.exists() and value is Range) and ((code.code='workflow' or code.code='task' or code.code='program') implies (value.exists() and (value is CodeableConcept or value is Reference)))))
2. UsageContext.code
Must Supporttrue
4. UsageContext.value[x]
[x] NoteSeeChoice of Data Typesfor further information about how to use [x]
Must Supporttrue
SlicingThis element introduces a set of slices on UsageContext.value[x]. The slices areUnordered and Open, and can be differentiated using the following discriminators:
  • type @ $this
  • 6. UsageContext.value[x]:valueCodeableConcept
    Slice NamevalueCodeableConcept
    Control0..1
    TypeCodeableConcept
    [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
    Must Supporttrue
    8. UsageContext.value[x]:valueCodeableConcept.coding
    Must Supporttrue
    10. UsageContext.value[x]:valueCodeableConcept.coding.system
    Must Supporttrue
    12. UsageContext.value[x]:valueCodeableConcept.coding.code
    Must Supporttrue
    14. UsageContext.value[x]:valueRange
    Slice NamevalueRange
    Control0..1
    TypeRange
    [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
    Must Supporttrue
    16. UsageContext.value[x]:valueRange.low
    Must Supporttrue
    18. UsageContext.value[x]:valueRange.high
    Must Supporttrue

    Guidance on how to interpret the contents of this table can be found here

    0. UsageContext
    Definition

    Specifies clinical/business/etc. metadata that can be used to retrieve, index and/or categorize an artifact. This metadata can either be specific to the applicable population (e.g., age category, DRG) or the specific context of care (e.g., venue, care setting, provider of care).

    ShortDescribes the context of use for a conformance or knowledge resource
    Control0..*
    This element is affected by the following invariants: ele-1
    Is Modifierfalse
    Must Supporttrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    sdc-uc-1: If code is gender, focus, user, venue or species, value must be CodeableConcept. If code is age, value must be Range. If code is workflow, task or program, value must be CodeableConcept or Reference (code.system!='http://terminology.hl7.org/CodeSystem/usage-context-type' or (((code.code='gender' or code.code='focus' or code.code='user' or code.code='venue' or code.code='species') implies value.exists() and value is CodeableConcept) and (code.code='age' implies value.exists() and value is Range) and ((code.code='workflow' or code.code='task' or code.code='program') implies (value.exists() and (value is CodeableConcept or value is Reference)))))
    2. UsageContext.code
    Definition

    A code that identifies the type of context being specified by this usage context.

    ShortType of context being specified
    Control1..1
    BindingUnless not suitable, these codes SHALL be taken from UsageContextTypehttp://hl7.org/fhir/ValueSet/usage-context-type
    (extensible to http://hl7.org/fhir/ValueSet/usage-context-type)

    A code that specifies a type of context being specified by a usage context.

    TypeCoding
    Is Modifierfalse
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    4. UsageContext.value[x]
    Definition

    A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

    ShortValue that defines the context
    Control1..1
    BindingFor example codes, see Context of Use ValueSethttp://hl7.org/fhir/ValueSet/use-context
    (example to http://hl7.org/fhir/ValueSet/use-context)

    A code that defines the specific value for the context being specified.

    TypeChoice of: CodeableConcept, Quantity, Range, Reference(PlanDefinition, ResearchStudy, InsurancePlan, HealthcareService, Group, Location, Organization)
    [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
    Is Modifierfalse
    Must Supporttrue
    Must Support TypesNo must-support rules about the choice of types/profiles
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    SlicingThis element introduces a set of slices on UsageContext.value[x]. The slices areUnordered and Open, and can be differentiated using the following discriminators:
    • type @ $this
    • 6. UsageContext.value[x]:valueCodeableConcept
      Slice NamevalueCodeableConcept
      Definition

      A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

      ShortValue that defines the context
      Control01..1
      BindingFor example codes, see Context of Use ValueSethttp://hl7.org/fhir/ValueSet/use-context
      (example to http://hl7.org/fhir/ValueSet/use-context)

      A code that defines the specific value for the context being specified.

      TypeCodeableConcept, Reference(PlanDefinition, ResearchStudy, InsurancePlan, HealthcareService, Group, Location, Organization), Quantity, Range
      [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
      Is Modifierfalse
      Must Supporttrue
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      8. UsageContext.value[x]:valueCodeableConcept.coding
      Definition

      A reference to a code defined by a terminology system.

      ShortCode defined by a terminology system
      Comments

      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.

      Control0..*
      TypeCoding
      Is Modifierfalse
      Must Supporttrue
      Summarytrue
      Requirements

      Allows for alternative encodings within a code system, and translations to other code systems.

      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      10. UsageContext.value[x]:valueCodeableConcept.coding.system
      Definition

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

      ShortIdentity of the terminology system
      Comments

      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 reference to some definition that establishes the system clearly and unambiguously.

      Control0..1
      Typeuri
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Must Supporttrue
      Summarytrue
      Requirements

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

      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      12. UsageContext.value[x]:valueCodeableConcept.coding.code
      Definition

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

      ShortSymbol in syntax defined by the system
      Control0..1
      Typecode
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Must Supporttrue
      Summarytrue
      Requirements

      Need to refer to a particular code in the system.

      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      14. UsageContext.value[x]:valueRange
      Slice NamevalueRange
      Definition

      A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

      ShortValue that defines the context
      Control01..1
      TypeRange, Reference(PlanDefinition, ResearchStudy, InsurancePlan, HealthcareService, Group, Location, Organization), Quantity, CodeableConcept
      [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
      Is Modifierfalse
      Must Supporttrue
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      16. UsageContext.value[x]:valueRange.low
      Definition

      The low limit. The boundary is inclusive.

      ShortLow limit
      Comments

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

      Control0..1
      TypeQuantity(SimpleQuantity)
      Is Modifierfalse
      Must Supporttrue
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      18. UsageContext.value[x]:valueRange.high
      Definition

      The high limit. The boundary is inclusive.

      ShortHigh limit
      Comments

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

      Control0..1
      TypeQuantity(SimpleQuantity)
      Is Modifierfalse
      Must Supporttrue
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))

      Guidance on how to interpret the contents of this table can be found here

      0. UsageContext
      Definition

      Specifies clinical/business/etc. metadata that can be used to retrieve, index and/or categorize an artifact. This metadata can either be specific to the applicable population (e.g., age category, DRG) or the specific context of care (e.g., venue, care setting, provider of care).

      ShortDescribes the context of use for a conformance or knowledge resource
      Control0..*
      This element is affected by the following invariants: ele-1
      Is Modifierfalse
      Must Supporttrue
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      sdc-uc-1: If code is gender, focus, user, venue or species, value must be CodeableConcept. If code is age, value must be Range. If code is workflow, task or program, value must be CodeableConcept or Reference (code.system!='http://terminology.hl7.org/CodeSystem/usage-context-type' or (((code.code='gender' or code.code='focus' or code.code='user' or code.code='venue' or code.code='species') implies value.exists() and value is CodeableConcept) and (code.code='age' implies value.exists() and value is Range) and ((code.code='workflow' or code.code='task' or code.code='program') implies (value.exists() and (value is CodeableConcept or value is Reference)))))
      2. UsageContext.id
      Definition

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

      ShortUnique id for inter-element referencing
      Control0..1
      Typestring
      Is Modifierfalse
      XML FormatIn the XML format, this property is represented as an attribute.
      Summaryfalse
      4. UsageContext.extension
      Definition

      May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

      ShortAdditional content defined by implementations
      Comments

      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.

      Control0..*
      TypeExtension
      Is Modifierfalse
      Summaryfalse
      Alternate Namesextensions, user content
      Invariantsele-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())
      SlicingThis element introduces a set of slices on UsageContext.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
      • value @ url
      • 6. UsageContext.code
        Definition

        A code that identifies the type of context being specified by this usage context.

        ShortType of context being specified
        Control1..1
        BindingUnless not suitable, these codes SHALL be taken from UsageContextType
        (extensible to http://hl7.org/fhir/ValueSet/usage-context-type)

        A code that specifies a type of context being specified by a usage context.

        TypeCoding
        Is Modifierfalse
        Must Supporttrue
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        8. UsageContext.value[x]
        Definition

        A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

        ShortValue that defines the context
        Control1..1
        BindingFor example codes, see Context of Use ValueSet
        (example to http://hl7.org/fhir/ValueSet/use-context)

        A code that defines the specific value for the context being specified.

        TypeChoice of: CodeableConcept, Quantity, Range, Reference(PlanDefinition, ResearchStudy, InsurancePlan, HealthcareService, Group, Location, Organization)
        [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
        Is Modifierfalse
        Must Supporttrue
        Must Support TypesNo must-support rules about the choice of types/profiles
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        SlicingThis element introduces a set of slices on UsageContext.value[x]. The slices areUnordered and Open, and can be differentiated using the following discriminators:
        • type @ $this
        • 10. UsageContext.value[x]:valueCodeableConcept
          Slice NamevalueCodeableConcept
          Definition

          A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

          ShortValue that defines the context
          Control0..1
          BindingFor example codes, see Context of Use ValueSet
          (example to http://hl7.org/fhir/ValueSet/use-context)

          A code that defines the specific value for the context being specified.

          TypeCodeableConcept
          [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
          Is Modifierfalse
          Must Supporttrue
          Summarytrue
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          12. UsageContext.value[x]:valueCodeableConcept.id
          Definition

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

          ShortUnique id for inter-element referencing
          Control0..1
          Typestring
          Is Modifierfalse
          XML FormatIn the XML format, this property is represented as an attribute.
          Summaryfalse
          14. UsageContext.value[x]:valueCodeableConcept.extension
          Definition

          May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

          ShortAdditional content defined by implementations
          Comments

          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.

          Control0..*
          TypeExtension
          Is Modifierfalse
          Summaryfalse
          Alternate Namesextensions, user content
          Invariantsele-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())
          SlicingThis element introduces a set of slices on UsageContext.value[x].extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
          • value @ url
          • 16. UsageContext.value[x]:valueCodeableConcept.coding
            Definition

            A reference to a code defined by a terminology system.

            ShortCode defined by a terminology system
            Comments

            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.

            Control0..*
            TypeCoding
            Is Modifierfalse
            Must Supporttrue
            Summarytrue
            Requirements

            Allows for alternative encodings within a code system, and translations to other code systems.

            Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
            18. UsageContext.value[x]:valueCodeableConcept.coding.id
            Definition

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

            ShortUnique id for inter-element referencing
            Control0..1
            Typestring
            Is Modifierfalse
            XML FormatIn the XML format, this property is represented as an attribute.
            Summaryfalse
            20. UsageContext.value[x]:valueCodeableConcept.coding.extension
            Definition

            May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

            ShortAdditional content defined by implementations
            Comments

            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.

            Control0..*
            TypeExtension
            Is Modifierfalse
            Summaryfalse
            Alternate Namesextensions, user content
            Invariantsele-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())
            SlicingThis element introduces a set of slices on UsageContext.value[x].coding.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
            • value @ url
            • 22. UsageContext.value[x]:valueCodeableConcept.coding.system
              Definition

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

              ShortIdentity of the terminology system
              Comments

              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 reference to some definition that establishes the system clearly and unambiguously.

              Control0..1
              Typeuri
              Is Modifierfalse
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Must Supporttrue
              Summarytrue
              Requirements

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

              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              24. UsageContext.value[x]:valueCodeableConcept.coding.version
              Definition

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

              ShortVersion of the system - if relevant
              Comments

              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.

              NoteThis is a business version Id, not a resource version Id (see discussion)
              Control0..1
              Typestring
              Is Modifierfalse
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Summarytrue
              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              26. UsageContext.value[x]:valueCodeableConcept.coding.code
              Definition

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

              ShortSymbol in syntax defined by the system
              Control0..1
              Typecode
              Is Modifierfalse
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Must Supporttrue
              Summarytrue
              Requirements

              Need to refer to a particular code in the system.

              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              28. UsageContext.value[x]:valueCodeableConcept.coding.display
              Definition

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

              ShortRepresentation defined by the system
              Control0..1
              Typestring
              Is Modifierfalse
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Summarytrue
              Requirements

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

              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              30. UsageContext.value[x]:valueCodeableConcept.coding.userSelected
              Definition

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

              ShortIf this coding was chosen directly by the user
              Comments

              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.

              Control0..1
              Typeboolean
              Is Modifierfalse
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Summarytrue
              Requirements

              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.

              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              32. UsageContext.value[x]:valueCodeableConcept.text
              Definition

              A human language representation of the concept as seen/selected/uttered by the user who entered the data and/or which represents the intended meaning of the user.

              ShortPlain text representation of the concept
              Comments

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

              Control0..1
              Typestring
              Is Modifierfalse
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Summarytrue
              Requirements

              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.

              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              34. UsageContext.value[x]:valueRange
              Slice NamevalueRange
              Definition

              A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

              ShortValue that defines the context
              Control0..1
              TypeRange
              [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
              Is Modifierfalse
              Must Supporttrue
              Summarytrue
              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              36. UsageContext.value[x]:valueRange.id
              Definition

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

              ShortUnique id for inter-element referencing
              Control0..1
              Typestring
              Is Modifierfalse
              XML FormatIn the XML format, this property is represented as an attribute.
              Summaryfalse
              38. UsageContext.value[x]:valueRange.extension
              Definition

              May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

              ShortAdditional content defined by implementations
              Comments

              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.

              Control0..*
              TypeExtension
              Is Modifierfalse
              Summaryfalse
              Alternate Namesextensions, user content
              Invariantsele-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())
              SlicingThis element introduces a set of slices on UsageContext.value[x].extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
              • value @ url
              • 40. UsageContext.value[x]:valueRange.low
                Definition

                The low limit. The boundary is inclusive.

                ShortLow limit
                Comments

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

                Control0..1
                TypeQuantity(SimpleQuantity)
                Is Modifierfalse
                Must Supporttrue
                Summarytrue
                Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
                42. UsageContext.value[x]:valueRange.high
                Definition

                The high limit. The boundary is inclusive.

                ShortHigh limit
                Comments

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

                Control0..1
                TypeQuantity(SimpleQuantity)
                Is Modifierfalse
                Must Supporttrue
                Summarytrue
                Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))