state

<xsd:element name="state" minOccurs="0" maxOccurs="1">
  <xsd:annotation>
    <xsd:documentation>
      <p>The state element should only be used for state variables. It replaces the label element used for other glyphs. It describes the text to be drawn inside the state variable.</p>
      <p>A state must have a value, a variable, or both. If it has both, they are rendered as a concatenated string with @ in between.</p>
    </xsd:documentation>
  </xsd:annotation>
  <xsd:complexType>
    <xsd:attribute name="value" type="xsd:string" use="optional">
      <xsd:annotation>
        <xsd:documentation>
          <p>The value attribute represents the state of the variable. It can be:
            <ul>
              <li>either from a predefined set of string (P, S, etc.) which correspond to specific SBO terms (cf. SBGN specs),</li>
              <li>or any arbitrary string.</li>
            </ul>
          </p>
        </xsd:documentation>
      </xsd:annotation>
    </xsd:attribute>
    <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>
  </xsd:complexType>
</xsd:element>