form

<xs:attribute name="form">
  <xs:annotation>
    <xs:documentation>Used to indicate the format of a list. In a "simple" list, li elements are not numbered or bulleted. In a "marked" list, the sequence of the list items is not critical, and a bullet, box, dash, or other character is displayed at the start of each item. In an "ordered" list, the sequence of the items is important, and each li is lettered or numbered. Style sheet functions should be used to specify the mark or numeration system for each li.</xs:documentation>
  </xs:annotation>
  <xs:simpleType>
    <xs:restriction base="xs:token">
      <xs:enumeration value="simple">
        <xs:annotation>
          <xs:documentation>Items are not numbered or bulleted.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="marked">
        <xs:annotation>
          <xs:documentation>Bullet, box, dash, or other character is displayed before each item.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
      <xs:enumeration value="ordered">
        <xs:annotation>
          <xs:documentation>Each item is numbered or lettered.</xs:documentation>
        </xs:annotation>
      </xs:enumeration>
    </xs:restriction>
  </xs:simpleType>
</xs:attribute>