XLink conformant elements must contain a type attribute. This is it's definition.
token
<simpleType name="basicLinkType" final="#all" >
<restriction base="token">
<enumeration value="simple" />
<enumeration value="extended" />
<enumeration value="locator" />
<enumeration value="arc" />
<enumeration value="resource" />
<enumeration value="title" />
<enumeration value="none" />
</restriction>
</simpleType>