---
type: "codesystem"
title: "Code System Hierarchy Meaning"
codesystem: "codesystem-hierarchy-meaning"
---
# Code System Hierarchy Meaning

- **Official URL**: http://hl7.org/fhir/codesystem-hierarchy-meaning
- **Version**: 6.0.0
- **Status**: active
- **Name**: CodeSystemHierarchyMeaning
- **Title**: Code System Hierarchy Meaning
- **Publisher**: HL7 International / Terminology Infrastructure
- **Description**: The meaning of the hierarchy of concepts in a code system.
- **Case Sensitive**: true
- **Content**: complete

## Concepts

| Code | Display | Definition |
| --- | --- | --- |
| grouped-by | Grouped By | No particular relationship between the concepts can be assumed, except what can be determined by inspection of the definitions of the elements (possible reasons to use this: importing from a source where this is not defined, or where various parts of the hierarchy have different meanings). |
| is-a | Is-A | A hierarchy where the child concepts have an IS-A relationship with the parents - that is, all the properties of the parent are also true for its child concepts. Not that is-a is a property of the concepts, so additional subsumption relationships may be defined using properties. |
| part-of | Part Of | Child elements list the individual parts of a composite whole (e.g. body site). |
| classified-with | Classified With | Child concepts in the hierarchy may have only one parent, and there is a presumption that the code system is a "closed world" meaning all things must be in the hierarchy. This results in concepts such as "not otherwise classified.". |

## CodeSystem XML



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

<CodeSystem xmlns="http://hl7.org/fhir">
  <id value="codesystem-hierarchy-meaning"/>
  <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/codesystem-hierarchy-meaning"/>
  <identifier>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.4.785"/>
  </identifier>
  <identifier>
    <use value="old"/>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.1.768"/>
  </identifier>
  <version value="6.0.0"/>
  <name value="CodeSystemHierarchyMeaning"/>
  <title value="Code System Hierarchy Meaning"/>
  <status value="active"/>
  <experimental value="false"/>
  <date value="2021-01-05T10:01:24+11:00"/>
  <publisher value="HL7 International / Terminology Infrastructure"/>
  <contact>
    <telecom>
      <system value="url"/>
      <value value="http://hl7.org/fhir"/>
    </telecom>
  </contact>
  <contact>
    <telecom>
      <system value="url"/>
      <value value="http://www.hl7.org/Special/committees/Vocab/index.cfm"/>
    </telecom>
  </contact>
  <description value="The meaning of the hierarchy of concepts in a code system."/>
  <caseSensitive value="true"/>
  <valueSet value="http://hl7.org/fhir/ValueSet/codesystem-hierarchy-meaning"/>
  <content value="complete"/>
  <concept>
    <code value="grouped-by"/>
    <display value="Grouped By"/>
    <definition value="No particular relationship between the concepts can be assumed, except what can be determined by inspection of the definitions of the elements (possible reasons to use this: importing from a source where this is not defined, or where various parts of the hierarchy have different meanings)."/>
  </concept>
  <concept>
    <code value="is-a"/>
    <display value="Is-A"/>
    <definition value="A hierarchy where the child concepts have an IS-A relationship with the parents - that is, all the properties of the parent are also true for its child concepts. Not that is-a is a property of the concepts, so additional subsumption relationships may be defined using properties."/>
  </concept>
  <concept>
    <code value="part-of"/>
    <display value="Part Of"/>
    <definition value="Child elements list the individual parts of a composite whole (e.g. body site)."/>
  </concept>
  <concept>
    <code value="classified-with"/>
    <display value="Classified With"/>
    <definition value="Child concepts in the hierarchy may have only one parent, and there is a presumption that the code system is a &quot;closed world&quot; meaning all things must be in the hierarchy. This results in concepts such as &quot;not otherwise classified.&quot;."/>
  </concept>
</CodeSystem>
```