Grouping into duplicates and non duplicate lists

Hi, I have scoured the web for help on this and have been through the archives
and Jenis' grouping pages but I cannot work it out. So here goes.

I am using xslt 1.0 and MSXML parser

I have an xml file that has a series of notes Like so
<CourseNote>
          <CourseNoteItem>
            <StudyGroupName>Aboriginal or Torres Strait
Islanders</StudyGroupName>
            <Year>2009</Year>
            <CourseNoteText>A</CourseNoteText>
            <StudyGroupOrder>2</StudyGroupOrder>
            <StudyGroupCode>ATSI</StudyGroupCode>
            <DisplaySequence>2</DisplaySequence>
          </CourseNoteItem>
          <CourseNoteItem>
            <StudyGroupName>Aboriginal or Torres Strait
Islanders</StudyGroupName>
            <Year>2009</Year>
            <CourseNoteText>B</CourseNoteText>
            <StudyGroupOrder>2</StudyGroupOrder>
            <StudyGroupCode>ATSI</StudyGroupCode>
            <DisplaySequence>5</DisplaySequence>
          </CourseNoteItem>
          <CourseNoteItem>
            <StudyGroupName>Award</StudyGroupName>
            <Year>2009</Year>
            <CourseNoteText>A</CourseNoteText>
            <StudyGroupOrder>1</StudyGroupOrder>
            <StudyGroupCode>AWD</StudyGroupCode>
            <DisplaySequence>2</DisplaySequence>
          </CourseNoteItem>
          <CourseNoteItem>
            <StudyGroupName>Award</StudyGroupName>
            <Year>2009</Year>
            <CourseNoteText>B</CourseNoteText>
            <StudyGroupOrder>1</StudyGroupOrder>
            <StudyGroupCode>AWD</StudyGroupCode>
            <DisplaySequence>5</DisplaySequence>
          </CourseNoteItem>
          <CourseNoteItem>
            <StudyGroupName>Award</StudyGroupName>
            <Year>2009</Year>
            <CourseNoteText>C</CourseNoteText>
            <StudyGroupOrder>1</StudyGroupOrder>
            <StudyGroupCode>AWD</StudyGroupCode>
            <DisplaySequence>7</DisplaySequence>
          </CourseNoteItem>
        </CourseNote>

There can be many different StudyGroupCodes, many CourseNoteTexts and many
Years. I would like to display a 'Generic' List of notes eg those that are
duplicated in every StudyGroup and then display lists of StudyGroups with the
CourseNoteTexts that are not duplicated in all other StudyGroups. I am
familiar with keys and get get lists of unigue items and group them but I
cannot exclude the items that do not appear in all StudyGroups...

Here is a fragment of my very poor solution which does not allow me to group
by StudyGroup the Notes that are not in all StudyGroups:

<ul>
<xsl:for-each select="CourseNoteItem[count(. | key('CN-T', concat(Year,
CourseNoteText))[1]) = 1]">
<xsl:if test="count(preceding-sibling::node()[name()=name(current())])=0">
<li>
<strong>Applies to all Study Groups</strong>
<br />
<xsl:copy-of select="CourseNoteText/node()" />
</li>
</xsl:if>
<xsl:if test="count(preceding-sibling::node()[name()=name(current())])!=0">
<li>
<strong>
<xsl:value-of select="StudyGroupName" />
</strong>
<br />
<xsl:copy-of select="CourseNoteText/node()" />
</li>
</xsl:if>
</xsl:for-each>
</ul>

Any help appreciated
Regards
 
Tim Cavanagh
Senior Technical Architect