n1:optional

Element Information

Model

n1:attribute | n1:choice | n1:ref
Children: n1:attribute, n1:choice, n1:ref

Used By

Elements n1:choice, n1:define, n1:element, n1:group, n1:list, n1:oneOrMore, n1:zeroOrMore

Source 

<xs:element name="optional">
  <xs:complexType>
    <xs:choice>
      <xs:element ref="n1:attribute"/>
      <xs:element ref="n1:choice"/>
      <xs:element ref="n1:ref"/>
    </xs:choice>
  </xs:complexType>
</xs:element>

Sample