grouping question.

Hi There,

I have some XML, part of which looks like:


<header>
      <usage ms="Cht" code="07051000"/>
      <usage ms="Ely" code="07051000"/>
      <usage ms="Evm" code="07051000"/>
      <usage ms="Evm" code="07053000"/>
      <usage ms="Evm" code="07055000"/>
      <usage ms="Glo" code="07053000"/>
      <usage ms="Hyd" code="07051000"/>
      <usage ms="Pet" code="07051000"/>
      <usage ms="Wcb" code="07051000"/>
      <usage ms="Wor" code="07051000"/>
</header>

My template for this matches the header and then for each usage element
goes and looks up the proper name of the manuscript (based on @ms) and
the proper name of the day (based on @code).

Currently the template in rough form looks like:

<xsl:template name="header">
<xsl:if test="usage">
  <div class="usagefooter">
  <hr />
    <ul>
<xsl:for-each select="//header/usage">
   <!-- Note: $mss document() declared outside this template -->
   <xsl:variable name="usagemss" 
select="$mss//witness[(_at_)sigil=$sigil]/@shortname"/>
   <xsl:variable name="filename" 
select="$mss//witness[(_at_)sigil=$sigil]/@filename"/>
   <xsl:variable name="daycode" select="@code" />
   <xsl:variable name="feasts" select="document('../../cantus/feast.xml')"/>
   <xsl:variable name="occasion" 
select="$feasts//feast[feastCode=$daycode]/occasion"/>
   <xsl:variable name="sigil" select="@ms"/>
     <xsl:if test="$filename != 'none'">
       <li> <xsl:value-of select="$usagemss"/>
       <xsl:if test="@id">(ID: <xsl:value-of select="@id"/>)</xsl:if>
       gives this in full for
       <a href="{concat('/cursus/ms/', substring-before($filename, '.'), '#', 
$sigil, '.', @code)}">
       <xsl:value-of select="$occasion"/></a>.</li>
            </xsl:if>
</xsl:for-each>
  </ul>
</div>
</xsl:if>
</xsl:template>


This produces output like:

<div class="usagefooter">
<hr>
<ul>
<li>Chertsey gives this in full for <a 
href="/cursus/ms/chertsey#Cht.07051000">Dominica de Passione</a>.</li>
<li>Ely gives this in full for <a href="/cursus/ms/ely#Ely.07051000">Dominica 
de Passione</a>.</li>
<li>Evesham gives this in full for <a 
href="/cursus/ms/evesham#Evm.07051000">Dominica de Passione</a>.</li>
<li>Evesham gives this in full for <a 
href="/cursus/ms/evesham#Evm.07053000">Feria 3 de Passione</a>.</li>
<li>Evesham gives this in full for <a 
href="/cursus/ms/evesham#Evm.07055000">Feria 5 de Passione</a>.</li>
<li>Gloucester gives this in full for <a 
href="/cursus/ms/gloucester#Glo.07053000">Feria 3 de Passione</a>.</li>
<li>Hyde gives this in full for <a href="/cursus/ms/hyde#Hyd.07051000">Dominica 
de Passione</a>.</li>
<li>Peterborough gives this in full for <a 
href="/cursus/ms/peterborough#Pet.07051000">Dominica de Passione</a>.</li>
<li>Winchcombe gives this in full for <a 
href="/cursus/ms/winchcombe#Wcb.07051000">Dominica de Passione</a>.</li>
<li>Worcester gives this in full for <a 
href="/cursus/ms/worcester#Wor.07051000">Dominica de Passione</a>.</li>
</ul>
</div>


This is fine, but as you can see the Evesham manuscript uses this
on 3 different days.  What I'd prefer is instead is something like:
<li>Evesham: <a href="/cursus/ms/evesham#Evm.07051000">Dominica de Passione</a>,
<a href="/cursus/ms/evesham#Evm.07053000">Feria 3 de Passione</a>,
<a href="/cursus/ms/evesham#Evm.07055000">Feria 5 de Passione</a>.</li>

So I want to group each of those by @ms, using only xslt 1 (sadly).

Although the <usage> elements are in alphabetic order by @ms I wouldn't
want to rely on that and just test the following-sibling.  If I was
to sort any order I'd want the <usage> elements as a whole sorted by
@ms and all those of the same @ms sorted by @code.

Suggestions?
-James
---
Dr James Cummings, Oxford Text Archive, 
James(_dot_)Cummings(_at_)ota(_dot_)ahds(_dot_)ac(_dot_)uk

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