controller 

There must be at least one controller element.

Element Information

Model

asset{0,1} , (skin | morph) , extra*
Children: asset, extra, morph, skin

Attributes

QName Type Fixed Default Use Inheritable Annotation
id xs:ID optional 
The id attribute is a text string containing the unique identifier of this element. This value 
must be unique within the instance document. Optional attribute.
name xs:token optional 
The name attribute is the text string name of this element. Optional attribute.

Source 

<xs:element name="controller" type="controller_type" maxOccurs="unbounded">
  <xs:annotation>
    <xs:documentation>There must be at least one controller element.</xs:documentation>
  </xs:annotation>
</xs:element>

Sample