Field with attribut in the schema.xml ?

[Bruno Mannina]

Dear,

I can't find how can I define in my schema.xml a field with this format?
My original format is:

<exch:inventors>

<exch:inventor>
<exch:inventor-name>
<name>WEBER WALTER</name>
</exch:inventor-name>
<residence>
<country>CH</country>
</residence>
</exch:inventor>

<exch:inventor>
<exch:inventor-name>
<name>ROSSI PASCAL</name>
</exch:inventor-name>
<residence>
<country>FR</country>
</residence>
</exch:inventor>

</exch:inventors>

I convert it to:
...
<field name="inventor">WEBER WALTER</field>
<field name="inventor">ROSSI PASCAL</field>
...

but how can I add Country code to the field without losing the link 
between inventor?
Can I use an attribut ?

Any idea are welcome :)

Thanks,
Bruno Mannina