Clarification on interpretation of xsi:type attributes

All the examples I have seen which use an xsi:type attribute to indicate
the
type of an element have used a prefixed name.

Given that xsi:type attribute values are treated as QNames during
validation,
I presume the normal namespace rules wrt default namespaces apply equally
to xsi:type attribute values i.e. I don't have to prefix the value if it is
coming from the
default namespace currently in scope.

Am I correct or off track?

Thanks
Michael