Boolean fails to be recognised in XML schema

I build an XML Schema with a boolean element as follows:

<xs:element name="SomeBooleanValue" type="xs:boolean" minOccurs="1" maxOccurs="1" default="False" />

I import it into my process as an XML field property. Thereafter I wish to see the element default to False in my process instance. This I did not see. On exporting the same XML Schema out of Studio I find that the line is now:

<xs:element name="SomeBooleanValue" type="xs:boolean" minOccurs="0" />

What is happening here? Why is the schema not being faithfully reproduced within Studio? Why must I lose all my validation, i.e. the reason to have a schema in the first place?

Can anybody through some light on this subject?

Graham