Summary

Mandatory: 3 elements (+3 nested mandatory elements)
Must-Support: 9 elements
Fixed Value: 5 elements
Prohibited: 7 elements

<!-- Example Lipid Profile -->

<Observation xmlns="http://hl7.org/fhir"
>
  <!-- from Element: extension -->
 <</id>

 <id value="[id]"/><!-- 0..1 Logical id of this artifact -->

 <meta><!--  0..1 Meta Metadata about the resource --></meta>
 <implicitRules value="[uri]"/><!--  0..1 A set of rules under which this content was created -->
 <language value="[code]"/><!--  0..1 Language of the resource content   -->
 <text><!--  0..1 Narrative 
     Text summary of the resource, for human interpretation --></text>
 <contained><!-- 0..* Resource Contained, inline Resources --></contained>
 <modifierExtension><!--  0..* Extension  Extensions that cannot be ignored  --></modifierExtension>
 <identifier><!--  0..* Identifier 
     Business Identifier for observation --></identifier>
 <basedOn><!--  0..* Reference(CarePlan) Fulfills plan, proposal or order --></basedOn>
 <partOf><!--  0..* Reference(MedicationAdministration) Part of referenced event --></partOf>
 <status value="[code]"/><!--  1..1 registered | preliminary | final | amended +   -->
 <category><!--  0..* CodeableConcept Classification of  type of observation   --></category>
 <code><!--  1..1 CodeableConcept Cholesterol   --></code>
 <subject><!--  0..1 Reference(Patient) 
     Who and/or what the observation is about --></subject>
 <focus><!--  0..* Reference(Resource) 
     What the observation is about, when it is not about the subject of record --></focus>
 <encounter><!--  0..1 Reference(Encounter) 
     Healthcare event during which this observation is made --></encounter>
 <effective[x]><!--  0..1 dateTime|Period|Timing|instant 
     Clinically relevant time/time-period for observation --></effective[x]>
 <issued value="[instant]"/><!--  0..1 Date/Time this version was made available -->
 <performer><!--  0..* Reference(Practitioner) 
     Who is responsible for the observation --></performer>
 <-- valueQuantity sliced by type:$this  in the specified orderClosed-->
 <valueQuantity>  0..1 Quantity  <!--  0..1 Cholesterol value -->
  <value value="[decimal]"/><!--  0..1 Actual numerical value -->
  <comparator value="[code]"/><!--  0..0 < | <= | >= | > - how to understand the value   -->
  <unit value="[string]"/><!--  1..1 Unit representation -->
  <system value="[uri]"/><!--  1..1 System that defines coded unit form -->
  <code value="[code]"/><!--  1..1 Coded form of the unit -->
 </valueQuantity>
 <dataAbsentReason><!--  0..1 CodeableConcept Why the result is missing   --></dataAbsentReason>
 <interpretation><!--  0..1 CodeableConcept + | ++ | +++ | - | -- | ---   --></interpretation>
 <note><!--  0..* Annotation Comments about result --></note>
 <bodySite><!--  0..1 CodeableConcept Observed body part   --></bodySite>
 <method><!--  0..1 CodeableConcept How it was done   --></method>
 <specimen><!--  0..1 Reference(Specimen) Specimen used for this observation --></specimen>
 <device><!--  0..1 Reference(Device) (Measurement) Device --></device>
 <

 <referenceRange>  1..1 BackboneElement  <!--  1..1 Provides guide for interpretation -->

  <modifierExtension><!--  0..* Extension  Extensions that cannot be ignored even if unrecognized  --></modifierExtension>
  <low><!--  0..0 Quantity 
      Low Range, if relevant --></low>
  <high><!--  1..1 Quantity 
      A fixed quantity (no comparator) --></high>
  <type><!--  0..0 CodeableConcept Reference range qualifier   --></type>
  <appliesTo><!--  0..0 CodeableConcept Reference range population   --></appliesTo>
  <age><!--  0..0 Range 
      Applicable age range, if relevant --></age>
  <text value="[string]"/><!--  0..1 Text based reference range in an observation -->
 </referenceRange>
 <hasMember><!--  0..0 Reference(Observation) 
     Related resource that belongs to the Observation group --></hasMember>
 <derivedFrom><!--  0..0 Reference(DocumentReference) 
     Related measurements the observation is made from --></derivedFrom>
 <

 <component>  0..* BackboneElement  <!--  0..* Component results -->

  <modifierExtension><!--  0..* Extension  Extensions that cannot be ignored even if unrecognized  --></modifierExtension>
  <code><!--  1..1 CodeableConcept Type of component observation (code / type)   --></code>
  <value[x]><!--  0..1 Quantity|CodeableConcept|string|
    

    boolean|integer|Range|Ratio|SampledData|time|dateTime|Period|Attachment 
      Actual component result --></value[x]>
  <dataAbsentReason><!--  0..1 CodeableConcept Why the component result is missing   --></dataAbsentReason>
  <interpretation><!--  0..* CodeableConcept High, low, normal, etc.   --></interpretation>
  <referenceRange><!-- See #Observation.referenceRange  Provides guide for interpretation of component result --></referenceRange>
 </component>
</Observation>

{ // Example Lipid Profile
  // from Element: extension
    "meta" : { Meta }, // C?Metadata about the resource
    "implicitRules" : "<uri>", // C?A set of rules under which this content was created
    "language" : "<code>", // C?Language of the resource content
    "text" : { Narrative }, // C?Text summary of the resource, for human interpretation
    "contained" : [{ Resource }], //Contained, inline Resources
    "modifierExtension" : [{ Extension }], // C?Extensions that cannot be ignored
    "identifier" : [{ Identifier }], // C?Business Identifier for observation
    "basedOn" : [{ Reference(CarePlan) }], // C?Fulfills plan, proposal or order
    "partOf" : [{ Reference(MedicationAdministration) }], // C?Part of referenced event
    "status" : "<code>", // C? R! registered | preliminary | final | amended +
    "category" : [{ CodeableConcept }], // C?Classification of  type of observation
    "code" : { CodeableConcept }, // C? R! 
    "subject" : { Reference(Patient) }, // C?Who and/or what the observation is about
    "focus" : [{ Reference(Resource) }], // C?What the observation is about, when it is not about the subject of record
    "encounter" : { Reference(Encounter) }, // C?Healthcare event during which this observation is made
// value[x]: Clinically relevant time/time-period for observation. One of these 4:
    "effectiveDateTime" : "<dateTime>", // C?Clinically relevant time/time-period for observation
    "effectivePeriod" : { Period }, // C?Clinically relevant time/time-period for observation
    "effectiveTiming" : { Timing }, // C?Clinically relevant time/time-period for observation
    "effectiveInstant" : "<instant>", // C?Clinically relevant time/time-period for observation
    "issued" : "<instant>", // C?Date/Time this version was made available
    "performer" : [{ Reference(Practitioner) }], // C?Who is responsible for the observation
    "valueQuantity" : [ //  sliced by type:$this  in the specified order, Closed 
      { // Cholesterol value // C?
        // from Element: extension
        "extension" : [ //  sliced by value:url  in the specified order, Open ]
        "value" : <decimal>, // C?Actual numerical value
        "unit" : "mmol/L", // C? R! 
        "system" : "http://unitsofmeasure.org", // C? R! 
        "code" : "mmol/L" // C? R! 
      }
    ],
    "dataAbsentReason" : { CodeableConcept }, // C?Why the result is missing
    "interpretation" : { CodeableConcept }, // C?+ | ++ | +++ | - | -- | ---
    "note" : [{ Annotation }], // C?Comments about result
    "bodySite" : { CodeableConcept }, // C?Observed body part
    "method" : { CodeableConcept }, // C?How it was done
    "specimen" : { Reference(Specimen) }, // C?Specimen used for this observation
    "device" : { Reference(Device) }, // C?(Measurement) Device
    "
    "

    "referenceRange" : { BackboneElement }, // C? R! Provides guide for interpretation
    "component" : [{ BackboneElement }], // C?Component results

  }

Summary

Mandatory: 3 elements (+3 nested mandatory elements)
Must-Support: 9 elements
Fixed Value: 5 elements
Prohibited: 7 elements

<!-- Example Lipid Profile -->

<Observation xmlns="http://hl7.org/fhir"
>
  <!-- from Element: extension -->
 <</id>

 <id value="[id]"/><!-- 0..1 Logical id of this artifact -->

 <meta><!--  0..1 Meta Metadata about the resource --></meta>
 <implicitRules value="[uri]"/><!--  0..1 A set of rules under which this content was created -->
 <language value="[code]"/><!--  0..1 Language of the resource content   -->
 <text><!--  0..1 Narrative 
     Text summary of the resource, for human interpretation --></text>
 <contained><!-- 0..* Resource Contained, inline Resources --></contained>
 <modifierExtension><!--  0..* Extension  Extensions that cannot be ignored  --></modifierExtension>
 <identifier><!--  0..* Identifier 
     Business Identifier for observation --></identifier>
 <basedOn><!--  0..* Reference(CarePlan) Fulfills plan, proposal or order --></basedOn>
 <partOf><!--  0..* Reference(MedicationAdministration) Part of referenced event --></partOf>
 <status value="[code]"/><!--  1..1 registered | preliminary | final | amended +   -->
 <category><!--  0..* CodeableConcept Classification of  type of observation   --></category>
 <code><!--  1..1 CodeableConcept Cholesterol   --></code>
 <subject><!--  0..1 Reference(Patient) 
     Who and/or what the observation is about --></subject>
 <focus><!--  0..* Reference(Resource) 
     What the observation is about, when it is not about the subject of record --></focus>
 <encounter><!--  0..1 Reference(Encounter) 
     Healthcare event during which this observation is made --></encounter>
 <effective[x]><!--  0..1 dateTime|Period|Timing|instant 
     Clinically relevant time/time-period for observation --></effective[x]>
 <issued value="[instant]"/><!--  0..1 Date/Time this version was made available -->
 <performer><!--  0..* Reference(Practitioner) 
     Who is responsible for the observation --></performer>
 <-- valueQuantity sliced by type:$this  in the specified orderClosed-->
 <valueQuantity>  0..1 Quantity  <!--  0..1 Cholesterol value -->
  <value value="[decimal]"/><!--  0..1 Actual numerical value -->
  <comparator value="[code]"/><!--  0..0 < | <= | >= | > - how to understand the value   -->
  <unit value="[string]"/><!--  1..1 Unit representation -->
  <system value="[uri]"/><!--  1..1 System that defines coded unit form -->
  <code value="[code]"/><!--  1..1 Coded form of the unit -->
 </valueQuantity>
 <dataAbsentReason><!--  0..1 CodeableConcept Why the result is missing   --></dataAbsentReason>
 <interpretation><!--  0..1 CodeableConcept + | ++ | +++ | - | -- | ---   --></interpretation>
 <note><!--  0..* Annotation Comments about result --></note>
 <bodySite><!--  0..1 CodeableConcept Observed body part   --></bodySite>
 <method><!--  0..1 CodeableConcept How it was done   --></method>
 <specimen><!--  0..1 Reference(Specimen) Specimen used for this observation --></specimen>
 <device><!--  0..1 Reference(Device) (Measurement) Device --></device>
 <

 <referenceRange>  1..1 BackboneElement  <!--  1..1 Provides guide for interpretation -->

  <modifierExtension><!--  0..* Extension  Extensions that cannot be ignored even if unrecognized  --></modifierExtension>
  <low><!--  0..0 Quantity 
      Low Range, if relevant --></low>
  <high><!--  1..1 Quantity 
      A fixed quantity (no comparator) --></high>
  <type><!--  0..0 CodeableConcept Reference range qualifier   --></type>
  <appliesTo><!--  0..0 CodeableConcept Reference range population   --></appliesTo>
  <age><!--  0..0 Range 
      Applicable age range, if relevant --></age>
  <text value="[string]"/><!--  0..1 Text based reference range in an observation -->
 </referenceRange>
 <hasMember><!--  0..0 Reference(Observation) 
     Related resource that belongs to the Observation group --></hasMember>
 <derivedFrom><!--  0..0 Reference(DocumentReference) 
     Related measurements the observation is made from --></derivedFrom>
 <

 <component>  0..* BackboneElement  <!--  0..* Component results -->

  <modifierExtension><!--  0..* Extension  Extensions that cannot be ignored even if unrecognized  --></modifierExtension>
  <code><!--  1..1 CodeableConcept Type of component observation (code / type)   --></code>
  <value[x]><!--  0..1 Quantity|CodeableConcept|string|
    

    boolean|integer|Range|Ratio|SampledData|time|dateTime|Period|Attachment 
      Actual component result --></value[x]>
  <dataAbsentReason><!--  0..1 CodeableConcept Why the component result is missing   --></dataAbsentReason>
  <interpretation><!--  0..* CodeableConcept High, low, normal, etc.   --></interpretation>
  <referenceRange><!-- See #Observation.referenceRange  Provides guide for interpretation of component result --></referenceRange>
 </component>
</Observation>

{ // Example Lipid Profile
  // from Element: extension
    "meta" : { Meta }, // C?Metadata about the resource
    "implicitRules" : "<uri>", // C?A set of rules under which this content was created
    "language" : "<code>", // C?Language of the resource content
    "text" : { Narrative }, // C?Text summary of the resource, for human interpretation
    "contained" : [{ Resource }], //Contained, inline Resources
    "modifierExtension" : [{ Extension }], // C?Extensions that cannot be ignored
    "identifier" : [{ Identifier }], // C?Business Identifier for observation
    "basedOn" : [{ Reference(CarePlan) }], // C?Fulfills plan, proposal or order
    "partOf" : [{ Reference(MedicationAdministration) }], // C?Part of referenced event
    "status" : "<code>", // C? R! registered | preliminary | final | amended +
    "category" : [{ CodeableConcept }], // C?Classification of  type of observation
    "code" : { CodeableConcept }, // C? R! 
    "subject" : { Reference(Patient) }, // C?Who and/or what the observation is about
    "focus" : [{ Reference(Resource) }], // C?What the observation is about, when it is not about the subject of record
    "encounter" : { Reference(Encounter) }, // C?Healthcare event during which this observation is made
// value[x]: Clinically relevant time/time-period for observation. One of these 4:
    "effectiveDateTime" : "<dateTime>", // C?Clinically relevant time/time-period for observation
    "effectivePeriod" : { Period }, // C?Clinically relevant time/time-period for observation
    "effectiveTiming" : { Timing }, // C?Clinically relevant time/time-period for observation
    "effectiveInstant" : "<instant>", // C?Clinically relevant time/time-period for observation
    "issued" : "<instant>", // C?Date/Time this version was made available
    "performer" : [{ Reference(Practitioner) }], // C?Who is responsible for the observation
    "valueQuantity" : [ //  sliced by type:$this  in the specified order, Closed 
      { // Cholesterol value // C?
        // from Element: extension
        "extension" : [ //  sliced by value:url  in the specified order, Open ]
        "value" : <decimal>, // C?Actual numerical value
        "unit" : "mmol/L", // C? R! 
        "system" : "http://unitsofmeasure.org", // C? R! 
        "code" : "mmol/L" // C? R! 
      }
    ],
    "dataAbsentReason" : { CodeableConcept }, // C?Why the result is missing
    "interpretation" : { CodeableConcept }, // C?+ | ++ | +++ | - | -- | ---
    "note" : [{ Annotation }], // C?Comments about result
    "bodySite" : { CodeableConcept }, // C?Observed body part
    "method" : { CodeableConcept }, // C?How it was done
    "specimen" : { Reference(Specimen) }, // C?Specimen used for this observation
    "device" : { Reference(Device) }, // C?(Measurement) Device
    "
    "

    "referenceRange" : { BackboneElement }, // C? R! Provides guide for interpretation
    "component" : [{ BackboneElement }], // C?Component results

  }