When working with namespaces, the schema author must decide whether the namespace of each element and attribute should be hidden or exposed in the document instance.
elementFormDefault="qualified | unqualified"
attributeFormDefault="qualified | unqualified"
By setting the elementFormDefault attribute, you can require the document instance to expose or hide namespace qualifications.
If you use elementFormDefault="qualified", the namespace of each element would have to be exposed in document instances.