Using xsd:type in xml files

Hi all,

I'm till trying to make sense of my problem xsd:( Actually the problem is
still centered on the same elements.

The xsd declares an element foo of complextype foo, then several elements
bar_x of complextype bar_x where bar_1, bar_2... are all derived by
extension from foo. (this is where we had the named complextype inside
named element before - I just extracted the complextypes declarations and
put them on the top level)

The xml files to validate then use

<foo xsd:type="whatever:bar_1"/>
<foo xsd:type="whatever:bar_2"/

to distinguish between all those foo variations.

My validator chokes on xsd:type and tells me it's not allowed there.

On my own I'd urge to use the named elements since we've declared them,
but I'd like to make sure no sort of trickery involving xsd:type is
possible (since whoever choose this construct must have had a good reason
to - at least I hope so). Is the problem just that the foo element do not
declare xsd:type as an allowed attribute or is this use totally contrary
to the xsd spirit ?

Regards,

-- 
Nicolas Mailhot