---
type: "codesystem"
title: "Example Onset Reason Codes"
codesystem: "ex-onsettype"
---
# Example Onset Reason Codes

- **Official URL**: http://hl7.org/fhir/ex-onsettype
- **Status**: draft
- **Name**: ExampleOnsetReasonCodes
- **Title**: Example Onset Reason Codes
- **Description**: This value set includes sample Onset reason which are used to identify the event for which the onset, starting date, is required.
- **Case Sensitive**: true
- **Content**: complete

## Concepts

| Code | Display | Definition |
| --- | --- | --- |
| lxm | Last Exam | Date of last examination. |
| sym | Start of Symptoms | Date when symptoms were first noticed. |
| lmn | Last Menstruation | Start date of last menstruation. |

## CodeSystem XML



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

<CodeSystem xmlns="http://hl7.org/fhir">
  <url value="http://hl7.org/fhir/ex-onsettype"/>
  <identifier>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.4.579"/>
  </identifier>
  <identifier>
    <use value="old"/>
    <system value="urn:ietf:rfc:3986"/>
    <value value="urn:oid:2.16.840.1.113883.4.642.1.571"/>
  </identifier>
  <name value="ExampleOnsetReasonCodes"/>
  <title value="Example Onset Reason Codes"/>
  <status value="draft"/>
  <experimental value="false"/>
  <description value="This value set includes sample Onset reason which are used to identify the event for which the onset, starting date, is required."/>
  <copyright value="This is an example set."/>
  <caseSensitive value="true"/>
  <content value="complete"/>
  <concept>
    <code value="lxm"/>
    <display value="Last Exam"/>
    <definition value="Date of last examination."/>
  </concept>
  <concept>
    <code value="sym"/>
    <display value="Start of Symptoms"/>
    <definition value="Date when symptoms were first noticed."/>
  </concept>
  <concept>
    <code value="lmn"/>
    <display value="Last Menstruation"/>
    <definition value="Start date of last menstruation."/>
  </concept>
</CodeSystem>
```