doubt on keyref

Here is a skeleton of xml, Can we have a keyref element refering to key of some other element?  In the  samples I f find  that the keyref element normally points to key element defined within the same context eleement.


<element name="A">
<xs:key name="key1"/>
</element>

<element name="B">
<xs:keyref name="key2" refer="key1"/>
</element>

waiting for your reply, thanks in advance.

-nandan