Key containing more than one 'target'?

Hi,

is it possible to generate a key that contains more "targets"?

in my xsl:

 <xsl:key name="ids" match="tc/pc/*[@id]" use="@id" />

...

<xsl:apply-templates select="*[@id and generate-id(.)= generate-id(key('ids', @id))]" />



my xml:

<tc id="123">
	<pc id="444">
	...
	</pc>
</tc>




I need a connection between tc-id and pc-id, so i thought i could be possible to make a key over pc and tc.

Has anybody a idea?

Thanks

Sven