Typos in Primer Section 3.1

In the third paragraph in Section 3.1 (below), it appears that "qualified"
should be changed to "unqualified".  (Also, note there is a small
agreement-related ungrammaticality in the 2nd sentence.)

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In po1.xsd we globally specify the qualification of elements and attributes by 
setting the values of both elementFormDefault and attributeFormDefault to
qualified. Strictly speaking, this is unnecessary because these are the default
values of the two attributes, but we do so to highlight the contrast between
this case and others we describe in subsequent sections. 
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-Adrian