variable 

<p>The variable attribute describes the site where the modification described by the value attribute occurs. It is:
  <ul>
    <li>optional when there is only one state variable on the parent EPN,</li>
    <li>required when there is more than one state variable the parent EPN.</li>
  </ul>
</p>

Attribute Information

Used By

Element glyph/state

Source 

<xsd:attribute name="variable" type="xsd:string" use="optional">
  <xsd:annotation>
    <xsd:documentation>
      <p>The variable attribute describes the site where the modification described by the value attribute occurs. It is:
        <ul>
          <li>optional when there is only one state variable on the parent EPN,</li>
          <li>required when there is more than one state variable the parent EPN.</li>
        </ul>
      </p>
    </xsd:documentation>
  </xsd:annotation>
</xsd:attribute>

Sample