FHIR CI-Build

This is the Continuous Integration Build of FHIR (will be incorrect/inconsistent at times).
See the Directory of published versions

Example StructureDefinition/Age (XML)

Modeling and Methodology Work GroupMaturity Level: N/AStandards Status: Informative

Raw XML (canonical form + also see XML Format Specification)

StructureDefinition for Age

<?xml version="1.0" encoding="UTF-8"?>

<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="Age"/> 
  <text> 
    <status value="generated"/> 
    <div xmlns="http://www.w3.org/1999/xhtml">
      <table border="0" cellpadding="0" cellspacing="0" style="border: 0px #F0F0F0 solid; font-size: 11px; font-family: verdana; vertical-align:
       top;">
        <tr style="border: 1px #F0F0F0 solid; font-size: 11px; font-family: verdana; vertical-align:
         top">
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="The logical name of the element">Name</a> 
          </th> 
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="Information about the use of the element">Flags</a> 
          </th> 
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="Minimum and Maximum # of times the the element can appear in the instance">Card.</a> 
          </th> 
          <th class="hierarchy" style="width: 100px">
            <a href="formats.html#table" title="Reference to the type of the element">Type</a> 
          </th> 
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="Additional information about the element">Description &amp; Constraints</a> 
            <span style="float: right">
              <a href="formats.html#table" title="Legend for this format">
                <img alt="doco" src="help16.png" style="background-color: inherit"/> 
              </a> 
            </span> 
          </th> 
        </tr> 
        <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color:
         white">
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(data:image/png;bas
          e64,iVBORw0KGgoAAAANSUhEUgAAAyAAAAACCAYAAACg/LjIAAAAJUlEQVR4Xu3IIQEAAAgDsHd9/w4EQIOamFnaBgAA4M
          MKAACAKwNp30CqZFfFmwAAAABJRU5ErkJggg==)">
            <img alt="." class="hierarchy" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAWCAYAAAABxvaqAAAACXBIWXMAAAsTAAALEwEAmpw
            YAAAAB3RJTUUH3wYeFzIs1vtcMQAAAB1pVFh0Q29tbWVudAAAAAAAQ3JlYXRlZCB3aXRoIEdJTVBkLmUHAAAAE0lEQVQI1
            2P4//8/AxMDAwNdCABMPwMo2ctnoQAAAABJRU5ErkJggg==" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data:image/png;base64,R0lGODlhEAAQAPZ/APrkusOiYvvfqbiXWaV2G+jGhdq1b8GgYf3v1frw3vTUlsWkZNewbcS
            jY/DQkad4Hb6dXv3u0f3v1ObEgfPTlerJiP3w1v79+e7OkPrfrfnjuNOtZPrpydaxa+/YrvvdpP779ZxvFPvnwKKBQaFyF
            /369M2vdaqHRPz58/HNh/vowufFhfroxO3OkPrluv779tK0e6JzGProwvrow9m4eOnIifPTlPDPkP78+Naxaf3v0/zowfX
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            PbPgrqZW+/QlPz48K2EMv36866OUPvowat8Ivvgq/Pbrvzgq/PguvrgrqN0Gda2evfYm9+7d/rpw9q6e/LSku/Rl/XVl/L
            Slfrkt+zVqe7Wqv3x1/bNffbOf59wFdS6if3u0vrqyP3owPvepfXQivDQkO/PkKh9K7STVf779P///wD/ACH5BAEKAH8AL
            AAAAAAQABAAAAemgH+CgxeFF4OIhBdKGwFChYl/hYwbdkoBPnaQkosbG3d3VEpSUlonUoY1Gzo6QkI8SrGxWBOFG4uySgY
            5ZWR3PFy2hnaWZXC/PHcPwkpJk1ShoHcxhQEXSUmtFy6+0iSFVResrjoTPDzdcoU+F65CduVU6KAhhQa3F8Tx8nchBoYuq
            oTLZoAKFRIhqGwqJAULFx0GYpBQeChRIR4TJm6KJMhQRUSBAAA7" style="background-color: white; background-color: inherit" title="Data Type"/>  
            <a href="datatypes-definitions.html#Age" title="Age : A duration of time during which an organism (or a process) has existed.">Age</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">
            <a href="elementdefinition-definitions.html#ElementDefinition.isSummary" style="padding-left: 3px; padding-right: 3px; color: black; null" title="This element is included in summaries">Σ</a> 
            <a href="versions.html#std-process" style="padding-left: 3px; padding-right: 3px; border: 1px grey solid; font-weight: bold;
             color: black; background-color: #fff5e6" title="Standards Status = Trial Use">TU</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px"/> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">
            <a href="datatypes.html#Quantity">Quantity</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0
           solid; padding:0px 4px 0px 4px">A duration of time during which an organism (or a process) has existed
            <br/>  
            <a href="valueset-age-units.html" title="Appropriate units for Age.">Common UCUM Codes for Age</a>  (
            <a href="terminologies.html#extensible" title="To be conformant, the concept in this element SHALL be from the specified value
             set if any of the codes within the value set can apply to the concept being communicated.
              If the value set does not cover the concept (based on human review), alternate
             codings (or, data type allowing, text) may be included instead.">Extensible</a>  but limited to 
            <a href="valueset-all-time-units.html">AllUCUMExpressionForTime</a> )
            <br/>  
            <span style="font-style: italic" title="age-1">+ Rule: There SHALL be a code if there is a value and it SHALL be an expression
               of time.  If system is present, it SHALL be UCUM.  If value is present, it SHALL
               be positive.</span> 
            <br/>  
            <br/>  Elements defined in Ancestors: 
            <a href="types.html#Element" title="Unique id for the element within a resource (for internal references). This may
             be any string value that does not contain spaces.">id</a> , 
            <a href="types.html#Element" title="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.">extension</a> , 
            <a href="datatypes.html#Quantity" title="The value of the measured amount. The value includes an implicit precision in the
             presentation of the value.">value</a> , 
            <a href="datatypes.html#Quantity" title="How the value should be understood and represented - whether the actual value is
             greater or less than the stated value due to measurement issues; e.g. if the comparator
             is &quot;&lt;&quot; , then the real value is &lt; stated value.">comparator</a> , 
            <a href="datatypes.html#Quantity" title="A human-readable form of the unit.">unit</a> , 
            <a href="datatypes.html#Quantity" title="The identification of the system that provides the coded form of the unit.">system</a> , 
            <a href="datatypes.html#Quantity" title="A computer processable form of the unit in some unit representation system.">code</a> 
          </td> 
        </tr> 

        <tr> 
          <td class="hierarchy" colspan="5">
            <br/>  
            <a href="formats.html#table" title="Legend for this format">
              <img alt="doco" src="help16.png" style="background-color: inherit"/>  Documentation for this format
            </a> 
          </td> 
        </tr> 
      </table> 
    </div> 
  </text> 
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
    <valueCode value="trial-use"/> 
  </extension> 
  <url value="http://hl7.org/fhir/StructureDefinition/Age"/> 
  <version value="5.0.0-cibuild"/> 
  <name value="Age"/> 
  <status value="draft"/> 
  <experimental value="false"/> 
  <date value="2022-11-23T14:50:25+00:00"/> 
  <publisher value="HL7 FHIR Standard"/> 
  <contact> 
    <telecom> 
      <system value="url"/> 
      <value value="http://hl7.org/fhir"/> 
    </telecom> 
  </contact> 
  <description value="Age Type: A duration of time during which an organism (or a process) has existed."/> 
  <fhirVersion value="5.0.0-cibuild"/> 
  <mapping> 
    <identity value="rim"/> 
    <uri value="http://hl7.org/v3"/> 
    <name value="RIM Mapping"/> 
  </mapping> 
  <mapping> 
    <identity value="v2"/> 
    <uri value="http://hl7.org/v2"/> 
    <name value="HL7 v2 Mapping"/> 
  </mapping> 
  <kind value="complex-type"/> 
  <abstract value="false"/> 
  <type value="Age"/> 
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Quantity"/> 
  <derivation value="specialization"/> 
  <snapshot> 
    <element id="Age">
      <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
        <valueCode value="trial-use"/> 
      </extension> 
      <path value="Age"/> 
      <short value="A duration of time during which an organism (or a process) has existed"/> 
      <definition value="A duration of time during which an organism (or a process) has existed."/> 
      <comment value="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."/> 
      <min value="0"/> 
      <max value="*"/> 
      <base> 
        <path value="Age"/> 
        <min value="0"/> 
        <max value="*"/> 
      </base> 
      <constraint> 
        <key value="age-1"/> 
        <severity value="error"/> 
        <human value="There SHALL be a code if there is a value and it SHALL be an expression of time.
          If system is present, it SHALL be UCUM.  If value is present, it SHALL be positive."/> 
        <expression value="(code.exists() or value.empty()) and (system.empty() or system = %ucum) and (value.empty()
         or value.hasValue().not() or value &gt; 0)"/> 
        <xpath value="(f:code or not(f:value)) and (not(exists(f:system)) or f:system/@value='http://unitsofmeasure
        .org') and (not(f:value/@value) or f:value/@value &gt;=0)"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Age"/> 
      </constraint> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <constraint> 
        <key value="qty-3"/> 
        <severity value="error"/> 
        <human value="If a code for the unit is present, the system SHALL also be present"/> 
        <expression value="code.empty() or system.exists()"/> 
        <xpath value="not(exists(f:code)) or exists(f:system)"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Quantity"/> 
      </constraint> 
      <isModifier value="false"/> 
      <binding> 
        <extension url="http://hl7.org/fhir/build/StructureDefinition/binding-definition">
          <valueString value="Appropriate units for Age."/> 
        </extension> 
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-maxValueSet">
          <valueCanonical value="http://hl7.org/fhir/ValueSet/all-time-units"/> 
        </extension> 
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="AgeUnits"/> 
        </extension> 
        <strength value="extensible"/> 
        <valueSet value="http://hl7.org/fhir/ValueSet/age-units"/> 
      </binding> 
      <mapping> 
        <identity value="v2"/> 
        <map value="SN (see also Range) or CQ"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="PQ, IVL&lt;PQ&gt;, MO, CO, depending on the values"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="PQ"/> 
      </mapping> 
    </element> 
    <element id="Age.id">
      <path value="Age.id"/> 
      <representation value="xmlAttr"/> 
      <short value="Unique id for inter-element referencing"/> 
      <definition value="Unique id for the element within a resource (for internal references). This may
       be any string value that does not contain spaces."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Element.id"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
    <!--  Note: special primitive values have a FHIRPath system type. e.g. this is compiler
       magic (j)  -->
      <type> 
        <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type">
          <valueUrl value="id"/> 
        </extension> 
        <code value="http://hl7.org/fhirpath/System.String"/> 
      </type> 
      <isModifier value="false"/> 
      <isSummary value="false"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value="n/a"/> 
      </mapping> 
    </element> 
    <element id="Age.extension">
      <path value="Age.extension"/> 
      <slicing> 
        <discriminator> 
          <type value="value"/> 
          <path value="url"/> 
        </discriminator> 
        <description value="Extensions are always sliced by (at least) url"/> 
        <rules value="open"/> 
      </slicing> 
      <short value="Additional content defined by implementations"/> 
      <definition value="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."/> 
      <comment value="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."/> 
      <alias value="extensions"/> 
      <alias value="user content"/> 
      <min value="0"/> 
      <max value="*"/> 
      <base> 
        <path value="Element.extension"/> 
        <min value="0"/> 
        <max value="*"/> 
      </base> 
      <type> 
        <code value="Extension"/> 
      </type> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <constraint> 
        <key value="ext-1"/> 
        <severity value="error"/> 
        <human value="Must have either extensions or value[x], not both"/> 
        <expression value="extension.exists() != value.exists()"/> 
        <xpath value="exists(f:extension)!=exists(f:*[starts-with(local-name(.), &quot;value&quot;)])"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Extension"/> 
      </constraint> 
      <isModifier value="false"/> 
      <isSummary value="false"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value="n/a"/> 
      </mapping> 
    </element> 
    <element id="Age.value">
      <path value="Age.value"/> 
      <short value="Numerical value (with implicit precision)"/> 
      <definition value="The value of the measured amount. The value includes an implicit precision in the
       presentation of the value."/> 
      <comment value="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)."/> 
      <requirements value="Precision is handled implicitly in almost all cases of measurement."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Quantity.value"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
      <type> 
        <code value="decimal"/> 
      </type> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <isModifier value="false"/> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="v2"/> 
        <map value="SN.2  / CQ - N/A"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="PQ.value, CO.value, MO.value, IVL.high or IVL.low depending on the value"/> 
      </mapping> 
    </element> 
    <element id="Age.comparator">
      <path value="Age.comparator"/> 
      <short value="&lt; | &lt;= | &gt;= | &gt; | ad - how to understand the value"/> 
      <definition value="How the value should be understood and represented - whether the actual value is
       greater or less than the stated value due to measurement issues; e.g. if the comparator
       is &quot;&lt;&quot; , then the real value is &lt; stated value."/> 
      <requirements value="Need a framework for handling measures where the value is &lt;5ug/L or &gt;400mg/L
       due to the limitations of measuring methodology."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Quantity.comparator"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
      <type> 
        <code value="code"/> 
      </type> 
      <meaningWhenMissing value="If there is no comparator, then there is no modification of the value"/> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <isModifier value="true"/> 
      <isModifierReason value="This is labeled as &quot;Is Modifier&quot; because the comparator modifies the
       interpretation of the value significantly. If there is no comparator, then there
       is no modification of the value"/> 
      <isSummary value="true"/> 
      <binding> 
        <extension url="http://hl7.org/fhir/build/StructureDefinition/binding-definition">
          <valueString value="How the Quantity should be understood and represented."/> 
        </extension> 
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="QuantityComparator"/> 
        </extension> 
        <strength value="required"/> 
        <valueSet value="http://hl7.org/fhir/ValueSet/quantity-comparator|5.0.0-cibuild"/> 
      </binding> 
      <mapping> 
        <identity value="v2"/> 
        <map value="SN.1  / CQ.1"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="IVL properties"/> 
      </mapping> 
    </element> 
    <element id="Age.unit">
      <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-translatable">
        <valueBoolean value="true"/> 
      </extension> 
      <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-translatable">
        <valueBoolean value="true"/> 
      </extension> 
      <path value="Age.unit"/> 
      <short value="Unit representation"/> 
      <definition value="A human-readable form of the unit."/> 
      <requirements value="There are many representations for units of measure and in many contexts, particular
       representations are fixed and required. I.e. mcg for micrograms."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Quantity.unit"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
      <type> 
        <code value="string"/> 
      </type> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <isModifier value="false"/> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="v2"/> 
        <map value="(see OBX.6 etc.) / CQ.2"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="PQ.unit"/> 
      </mapping> 
    </element> 
    <element id="Age.system">
      <path value="Age.system"/> 
      <short value="System that defines coded unit form"/> 
      <definition value="The identification of the system that provides the coded form of the unit."/> 
      <requirements value="Need to know the system that defines the coded form of the unit."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Quantity.system"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
      <type> 
        <code value="uri"/> 
      </type> 
      <condition value="qty-3"/> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <isModifier value="false"/> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="v2"/> 
        <map value="(see OBX.6 etc.) / CQ.2"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="CO.codeSystem, PQ.translation.codeSystem"/> 
      </mapping> 
    </element> 
    <element id="Age.code">
      <extension url="http://hl7.org/fhir/build/StructureDefinition/no-binding">
        <valueBoolean value="true"/> 
      </extension> 
      <path value="Age.code"/> 
      <short value="Coded form of the unit"/> 
      <definition value="A computer processable form of the unit in some unit representation system."/> 
      <comment value="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."/> 
      <requirements value="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."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Quantity.code"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
      <type> 
        <code value="code"/> 
      </type> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() or (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/> 
      </constraint> 
      <isModifier value="false"/> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="v2"/> 
        <map value="(see OBX.6 etc.) / CQ.2"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="PQ.code, MO.currency, PQ.translation.code"/> 
      </mapping> 
    </element> 
  </snapshot> 
  <differential> 
    <element id="Age">
      <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
        <valueCode value="trial-use"/> 
      </extension> 
      <path value="Age"/> 
      <short value="A duration of time during which an organism (or a process) has existed"/> 
      <definition value="A duration of time during which an organism (or a process) has existed."/> 
      <min value="0"/> 
      <max value="*"/> 
      <constraint> 
        <key value="age-1"/> 
        <severity value="error"/> 
        <human value="There SHALL be a code if there is a value and it SHALL be an expression of time.
          If system is present, it SHALL be UCUM.  If value is present, it SHALL be positive."/> 
        <expression value="(code.exists() or value.empty()) and (system.empty() or system = %ucum) and (value.empty()
         or value.hasValue().not() or value &gt; 0)"/> 
        <xpath value="(f:code or not(f:value)) and (not(exists(f:system)) or f:system/@value='http://unitsofmeasure
        .org') and (not(f:value/@value) or f:value/@value &gt;=0)"/> 
        <source value="http://hl7.org/fhir/StructureDefinition/Age"/> 
      </constraint> 
      <binding> 
        <extension url="http://hl7.org/fhir/build/StructureDefinition/binding-definition">
          <valueString value="Appropriate units for Age."/> 
        </extension> 
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-maxValueSet">
          <valueCanonical value="http://hl7.org/fhir/ValueSet/all-time-units"/> 
        </extension> 
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="AgeUnits"/> 
        </extension> 
        <strength value="extensible"/> 
        <valueSet value="http://hl7.org/fhir/ValueSet/age-units"/> 
      </binding> 
      <mapping> 
        <identity value="rim"/> 
        <map value="PQ"/> 
      </mapping> 
    </element> 
  </differential> 
</StructureDefinition> 

Usage note: every effort has been made to ensure that the examples are correct and useful, but they are not a normative part of the specification.