<xs:restriction base="xs:NMTOKEN"> <xs:enumeration value="target_right"/>
<xs:enumeration value="target"/>
<xs:enumeration value="target_left"/>
<xs:enumeration value="target_on_edge"/>
<xs:enumeration value="source_right"/>
<xs:enumeration value="source"/>
<xs:enumeration value="source_left"/>
<xs:enumeration value="source_on_edge"/>
<xs:enumeration value="center_right"/>
<xs:enumeration value="center"/>
<xs:enumeration value="center_left"/>
<xs:enumeration value="center_on_edge"/>
<xs:enumeration value="anywhere"/>
<xs:enumeration value="on_edge"/>
<xs:enumeration value="left"/>
<xs:enumeration value="right"/>
</xs:restriction>