xnotes, etc.

OK, I've modified my notes schema and the corresponding mods-bn schema 
to something closer to xnotes.  Feedback?

An example instance that validates against mods-bn.rnc in nxml mode:

<?xml version="1.0" encoding="utf-8"?>
<modsCollection xmlns="http://www.loc.gov/mods/v3">
   <mods ID="herod2002a">
<!-- name with roles, not authors; captures a wider range of content 
more accurately  -->
     <name type="personal">
       <namePart type="given">Andrew</namePart>
       <namePart type="family">Herod</namePart>
       <role>
	<roleTerm type="text">editor</roleTerm>
       </role>
     </name>
     <name type="personal">
       <namePart type="given">Melissa</namePart>
       <namePart type="family">Wright</namePart>
       <role>
	<roleTerm type="text">editor</roleTerm>
       </role>
     </name>
     <titleInfo>
<!-- title and subtitle, language attribute, full and abbreviated  -->
       <title>Geographies of Power</title>
       <subTitle>Placing Scale</subTitle>
     </titleInfo>
     <originInfo>
<!-- originInfo broader than simply for published works -->
       <publisher>Blackwell Publishing</publisher>
       <place>
	<placeTerm type="text">New York</placeTerm>
       </place>
       <dateIssued>2002</dateIssued>
       <issuance>monographic</issuance>
     </originInfo>
     <typeOfResource>text</typeOfResource>
     <genre>book</genre>
<!-- subject/topic distinction allows grouping of terms  -->
     <subject>
       <topic>power</topic>
       <topic>scale</topic>
       <topic>geography</topic>
      </subject>
<!-- extension allows anything to be added that's namespaced -->
     <extension>
       <xnote xmlns="http://refdb.sourceforge.net/xnotes-ns">
	<note user="darcusb">
	  <p>Brings together new work on the <socalled>politics of
	  scale</socalled>.</p>
	</note>
       </xnote>
     </extension>
   </mods>
</modsCollection>