---
type: "codesystem"
title: "Filter Operator"
codesystem: "filter-operator"
---
# Filter Operator

- **Official URL**: http://hl7.org/fhir/filter-operator
- **Version**: 6.0.0
- **Status**: active
- **Name**: FilterOperator
- **Title**: Filter Operator
- **Publisher**: HL7 (FHIR Project)
- **Description**: The kind of operation to perform as a part of a property based filter.
- **Case Sensitive**: true
- **Content**: complete

## Narrative

This code system http://hl7.org/fhir/filter-operator defines the following codes:

| **Code** | **Display** | **Definition** | **Comments** |
| --- | --- | --- | --- |
| \= | Equals | The specified property of the code equals the provided value. |  |
| is-a | Is A (by subsumption) | Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, including the provided concept itself (include descendant codes and self). | The definition of is-a is that all the properties of the value are true for the specified property of the code, which means that a code has an is-a relationship with itself. To exclude the root code, use descendent-of |
| descendent-of | Descendent Of (by subsumption) | Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, excluding the provided concept itself i.e. include descendant codes only). | The definition of is-a is that all the properties of the value are true for the specified property of the code. Spelling note: "descendant" is a more correct spelling, but the spelling "descendent" is maintained in the code for backwards compatibility reasons |
| is-not-a | Not (Is A) (by subsumption) | The specified property of the code does not have an is-a relationship with the provided value. |  |
| regex | Regular Expression | The specified property of the code matches the regex specified in the provided value. |  |
| in | In Set | The specified property of the code is in the set of codes or concepts specified in the provided value (comma-separated list). |  |
| not-in | Not in Set | The specified property of the code is not in the set of codes or concepts specified in the provided value (comma-separated list). |  |
| generalizes | Generalizes (by Subsumption) | Includes all concept ids that have a transitive is-a relationship from the concept Id provided as the value, including the provided concept itself (i.e. include ancestor codes and self). | The definition of is-a is that all the properties of the value are true for the specified property of the code, which means that a code has an is-a relationship with itself. To exclude the root code, add it explicitly to as an exclude |
| exists | Exists | The specified property of the code has at least one value (if the specified value is true; if the specified value is false, then matches when the specified property of the code has no values). |  |
| child-of | Child Of | Only concepts with a direct hierarchical relationship to the index code and no other concepts. This does not include the index code in the output. |  |
| descendent-leaf | Descendent Leaf | Includes concept ids that have a transitive is-a relationship with the concept Id provided as the value, but which do not have any concept ids with transitive is-a relationships with themselves. |  |

## Concepts

| Code | Display | Definition |
| --- | --- | --- |
| = | Equals | The specified property of the code equals the provided value. |
| is-a | Is A (by subsumption) | Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, including the provided concept itself (include descendant codes and self). |
| descendent-of | Descendent Of (by subsumption) | Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, excluding the provided concept itself (i.e. include descendant codes only). |
| is-not-a | Not (Is A) (by subsumption) | The specified property of the code does not have an is-a relationship with the provided value. |
| regex | Regular Expression | The specified property of the code  matches the regex specified in the provided value. |
| in | In Set | The specified property of the code is in the set of codes or concepts specified in the provided value (comma-separated list). |
| not-in | Not in Set | The specified property of the code is not in the set of codes or concepts specified in the provided value (comma-separated list). |
| generalizes | Generalizes (by Subsumption) | Includes all concept ids that have a transitive is-a relationship from the concept Id provided as the value, including the provided concept itself (i.e. include ancestor codes and self). |
| child-of | Child Of | Only concepts with a direct hierarchical relationship to the index code and no other concepts. This does not include the index code in the output. |
| descendent-leaf | Descendent Leaf | Includes concept ids that have a transitive is-a relationship with the concept Id provided as the value, but which do not have any concept ids with transitive is-a relationships with themselves. |
| exists | Exists | The specified property of the code has at least one value (if the specified value is true; if the specified value is false, then matches when the specified property of the code has no values). |

## CodeSystem XML



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

<CodeSystem xmlns="http://hl7.org/fhir">
  <id value="filter-operator"/>
  <meta>
    <lastUpdated value="2021-01-05T10:01:24.148+11:00"/>
  </meta>
  <text>
    <status value="extensions"/>
    <div xmlns="http://www.w3.org/1999/xhtml">
      
      
      
      
      <p>This code system http://hl7.org/fhir/filter-operator defines the following codes:</p>
      
      
      
      
      <table class="codes">
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">
            
            
            
            
            <b>Code</b>
          
          
          
          
          </td>
          
          
          
          
          <td>
            
            
            
            
            <b>Display</b>
          
          
          
          
          </td>
          
          
          
          
          <td>
            
            
            
            
            <b>Definition</b>
          
          
          
          
          </td>
          
          
          
          
          <td>
            
            
            
            
            <b>Comments</b>
          
          
          
          
          </td>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">=
            
            
            
            
            <a name="filter-operator-.61"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Equals</td>
          
          
          
          
          <td>The specified property of the code equals the provided value.</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">is-a
            
            
            
            
            <a name="filter-operator-is-a"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Is A (by subsumption)</td>
          
          
          
          
          <td>Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, including the provided concept itself (include descendant codes and self).</td>
          
          
          
          
          <td>The definition of is-a is that all the properties of the value are true for the specified property of the code, which means that a code has an is-a relationship with itself. To exclude the root code, use descendent-of</td>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">descendent-of
            
            
            
            
            <a name="filter-operator-descendent-of"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Descendent Of (by subsumption)</td>
          
          
          
          
          <td>Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, excluding the provided concept itself i.e. include descendant codes only).</td>
          
          
          
          
          <td>The definition of is-a is that all the properties of the value are true for the specified property of the code. 

Spelling note: &quot;descendant&quot; is a more correct spelling, but the spelling &quot;descendent&quot; is maintained in the code for backwards compatibility reasons</td>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">is-not-a
            
            
            
            
            <a name="filter-operator-is-not-a"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Not (Is A) (by subsumption)</td>
          
          
          
          
          <td>The specified property of the code does not have an is-a relationship with the provided value.</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">regex
            
            
            
            
            <a name="filter-operator-regex"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Regular Expression</td>
          
          
          
          
          <td>The specified property of the code  matches the regex specified in the provided value.</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">in
            
            
            
            
            <a name="filter-operator-in"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>In Set</td>
          
          
          
          
          <td>The specified property of the code is in the set of codes or concepts specified in the provided value (comma-separated list).</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">not-in
            
            
            
            
            <a name="filter-operator-not-in"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Not in Set</td>
          
          
          
          
          <td>The specified property of the code is not in the set of codes or concepts specified in the provided value (comma-separated list).</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">generalizes
            
            
            
            
            <a name="filter-operator-generalizes"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Generalizes (by Subsumption)</td>
          
          
          
          
          <td>Includes all concept ids that have a transitive is-a relationship from the concept Id provided as the value, including the provided concept itself (i.e. include ancestor codes and self).</td>
          
          
          
          
          <td>The definition of is-a is that all the properties of the value are true for the specified property of the code, which means that a code has an is-a relationship with itself. To exclude the root code, add it explicitly to as an exclude</td>
        
        
        
        
        </tr>
        
        
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">exists
            
            
            
            
            <a name="filter-operator-exists"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Exists</td>
          
          
          
          
          <td>The specified property of the code has at least one value (if the specified value is true; if the specified value is false, then matches when the specified property of the code has no values).</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
		
		
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">child-of
            
            
            
            
            <a name="filter-operator-child-of"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Child Of</td>
          
          
          
          
          <td>Only concepts with a direct hierarchical relationship to the index code and no other concepts. This does not include the index code in the output.</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
		
		
        
        
        <tr>
          
          
          
          
          <td style="white-space:nowrap">descendent-leaf
            
            
            
            
            <a name="filter-operator-descendent-leaf"> </a>
          
          
          
          
          </td>
          
          
          
          
          <td>Descendent Leaf</td>
          
          
          
          
          <td>Includes concept ids that have a transitive is-a relationship with the concept Id provided as the value, but which do not have any concept ids with transitive is-a relationships with themselves.</td>
          
          
          
          
          <td/>
        
        
        
        
        </tr>
      
      
      
      
      </table>
    
    
    
    
    </div>
  </text>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
    <valueCode value="vocab"/>
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
    <valueCode value="normative"/>
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
    <valueInteger value="5"/>
  </extension>
  <url value="http://hl7.org/fhir/filter-operator"/>
  <identifier>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.4.479"/>
  </identifier>
  <identifier>
    <use value="old"/>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.1.472"/>
  </identifier>
  <identifier>
    <use value="old"/>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.2.280"/>
  </identifier>
  <version value="6.0.0"/>
  <name value="FilterOperator"/>
  <title value="Filter Operator"/>
  <status value="active"/>
  <experimental value="false"/>
  <date value="2021-01-05T10:01:24+11:00"/>
  <publisher value="HL7 (FHIR Project)"/>
  <contact>
    <telecom>
      <system value="url"/>
      <value value="http://hl7.org/fhir"/>
    </telecom>
    <telecom>
      <system value="email"/>
      <value value="fhir@lists.hl7.org"/>
    </telecom>
  </contact>
  <description value="The kind of operation to perform as a part of a property based filter."/>
  <caseSensitive value="true"/>
  <valueSet value="http://hl7.org/fhir/ValueSet/filter-operator"/>
  <content value="complete"/>
  <concept>
    <code value="="/>
    <display value="Equals"/>
    <definition value="The specified property of the code equals the provided value."/>
  </concept>
  <concept>
    <code value="is-a"/>
    <display value="Is A (by subsumption)"/>
    <definition value="Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, including the provided concept itself (include descendant codes and self)."/>
    <property>
      <code value="comments"/>
      <valueString value="The definition of is-a is that all the properties of the value are true for the specified property of the code, which means that a code has an is-a relationship with itself. To exclude the root code, use descendent-of"/>
    </property>
  </concept>
  <concept>
    <code value="descendent-of"/>
    <display value="Descendent Of (by subsumption)"/>
    <definition value="Includes all concept ids that have a transitive is-a relationship with the concept Id provided as the value, excluding the provided concept itself (i.e. include descendant codes only)."/>
    <property>
      <code value="comments"/>
      <valueString value="The definition of is-a is that all the properties of the value are true for the specified property of the code. &#xA;&#xA;Spelling note: &quot;descendant&quot; is a more correct spelling, but the spelling &quot;descendent&quot; is maintained in the code for backwards compatibility reasons"/>
    </property>
  </concept>
  <concept>
    <code value="is-not-a"/>
    <display value="Not (Is A) (by subsumption)"/>
    <definition value="The specified property of the code does not have an is-a relationship with the provided value."/>
  </concept>
  <concept>
    <code value="regex"/>
    <display value="Regular Expression"/>
    <definition value="The specified property of the code  matches the regex specified in the provided value."/>
  </concept>
  <concept>
    <code value="in"/>
    <display value="In Set"/>
    <definition value="The specified property of the code is in the set of codes or concepts specified in the provided value (comma-separated list)."/>
  </concept>
  <concept>
    <code value="not-in"/>
    <display value="Not in Set"/>
    <definition value="The specified property of the code is not in the set of codes or concepts specified in the provided value (comma-separated list)."/>
  </concept>
  <concept>
    <code value="generalizes"/>
    <display value="Generalizes (by Subsumption)"/>
    <definition value="Includes all concept ids that have a transitive is-a relationship from the concept Id provided as the value, including the provided concept itself (i.e. include ancestor codes and self)."/>
    <property>
      <code value="comments"/>
      <valueString value="The definition of is-a is that all the properties of the value are true for the specified property of the code, which means that a code has an is-a relationship with itself. To exclude the root code, add it explicitly to as an exclude"/>
    </property>
  </concept>
  <concept>
    <code value="child-of"/>
    <display value="Child Of"/>
    <definition value="Only concepts with a direct hierarchical relationship to the index code and no other concepts. This does not include the index code in the output."/>
  </concept>
  <concept>
    <code value="descendent-leaf"/>
    <display value="Descendent Leaf"/>
    <definition value="Includes concept ids that have a transitive is-a relationship with the concept Id provided as the value, but which do not have any concept ids with transitive is-a relationships with themselves."/>
  </concept>
  <concept>
    <code value="exists"/>
    <display value="Exists"/>
    <definition value="The specified property of the code has at least one value (if the specified value is true; if the specified value is false, then matches when the specified property of the code has no values)."/>
  </concept>
</CodeSystem>
```