Difficulty with semi-recursive operation in XSLT

Happy Holidays, Everyone.

Here is my XML:

<?xml version="1.0" encoding="UTF-8"?>
<worksheet version="12.0.0.1" xmlns="urn:schemas-mathsoft-com:mcws"
xmlns:ml="urn:schemas-mathsoft-com:mcml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:schemas-mathsoft-com:mcws ../Worksheet.xsd">
	<settings>
		<presentation>
			<pageModel>
			 <margins left="1.0" right="0.5" top="1.0"
bottom="0.5"/>
			 <header use-full-page-width="false"></header>
			 <footer use-full-page-width="false"></footer>
			</pageModel>
		</presentation>
		<editor>
			<ruler ruler-unit="in" is-visible="false">
			 <tabs>			
			  <tab position="0.5" show-guide="false"/>
			  <tab position="1.0" show-guide="false"/>
			 </tabs>
			</ruler>
		</editor>
	</settings>
	<regions>
	 <region id="1">
	  <text>
	   <p style="Normal" tabs="0.2 1.2 2.2">
		Once upon a time, there was a <b>dark</b> and
<i>stormy</i> sea.  		Nobody could be<br/>certain what lay
beneath it's churning 			surface.<br/>
		<tab/>One<tab/>Green<tab/>Octopus<br/>
		<tab/>Two<tab/>Red<tab/>Sharks<br/>
		Or something far more sinister?
	   </p>			
	  </text>
	 </region>
	</regions>
</worksheet>

And here is the XSL-FO output I'm trying to get:

<?xml version="1.0" encoding="utf-8"?>
<root xmlns="http://www.w3.org/1999/XSL/Format"
       font-family="Times" font-size="20pt">

   <layout-master-set>
     <simple-page-master master-name="frame"
                         page-height="11in" page-width="8.5in"
                         margin-top="1in" margin-bottom="1in"
                         margin-left="0.5in" margin-right="0.5in">

     <!-- NOTE: the useable page-width is 7.5in, the usable page-height
is 	9in -->

       <region-body region-name="frame-body"/>
     </simple-page-master>
   </layout-master-set>

   <page-sequence master-reference="frame">
     <flow flow-name="frame-body">
       <block>
         Once upon a time, there was a <inline
font-weight="bold">dark</inline> and <inline font-style="italic">stormy
</inline> sea.  Nobody could be <block/>certain what lay beneath it's
churning surface.<block/>
       <table>
         <table-column column-width="0.2in"/>
         <table-column column-width="1.0in"/>
         <table-column column-width="1.0in"/>
         <!-- useable width of the last column, after there are no more
tabs: total usable page width minus total width of columns = (7.5in -
2.2in) = 5.3in-->
         <table-column column-width="5.3in"/>
         <table-body>
           <table-row>
             <table-cell><block/></table-cell>
             <table-cell><block>One</block></table-cell>
             <table-cell><block>Green</block></table-cell>
             <table-cell><block>Octopus</block></table-cell>
           </table-row>
           <table-row>
             <table-cell><block/></table-cell>
             <table-cell><block>Two</block></table-cell>
             <table-cell><block>Red</block></table-cell>
             <table-cell><block>Sharks</block></table-cell>
           </table-row>
         </table-body>
       </table>
       Or something far more sinister?
	</block>
     </flow>
   </page-sequence>
</root>

Here's what I have so far for a stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:fo="http://www.w3.org/1999/XSL/Format"
xmlns:ws="urn:schemas-mathsoft-com:mcws"
xmlns:ml="urn:schemas-mathsoft-com:mcml"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<xsl:output method="xml" indent="yes"/>
	<xsl:template match="ws:worksheet">
		<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
			<fo:layout-master-set>
				<fo:simple-page-master
master-name="worksheet">
					<xsl:element
name="fo:region-body">
						<xsl:attribute
name="region-name"><xsl:text>xsl-region-body</xsl:text></xsl:attribute>
						<xsl:attribute
name="margin-top"><xsl:value-of
select="settings/presentation/pageModel/margins/@top"/></xsl:attribute>
						<xsl:attribute
name="margin-bottom"><xsl:value-of
select="settings/presentation/pageModel/margins/@bottom"/></xsl:attribut
e>
						<xsl:attribute
name="margin-left"><xsl:value-of
select="settings/presentation/pageModel/margins/@left"/></xsl:attribute>
						<xsl:attribute
name="margin-right"><xsl:value-of
select="settings/presentation/pageModel/margins/@right"/></xsl:attribute
>
					</xsl:element>
					<fo:region-before
precedence="true" border="none" region-name="xsl-region-before"
extent="0.5in" display-align="before"/>
					<fo:region-after
precedence="true" border="none" region-name="xsl-region-after"
extent="0.5in" display-align="after"/>
				</fo:simple-page-master>
			</fo:layout-master-set>
			<fo:page-sequence master-reference="worksheet">
				<fo:flow flow-name="xsl-region-body">
					<xsl:element name="fo:block">
						<!-- just a little extra
padding -->
						<xsl:attribute
name="border-width"><xsl:text>2em</xsl:text></xsl:attribute>
						<xsl:attribute
name="border-style"><xsl:text>none</xsl:text></xsl:attribute>
						<xsl:apply-templates/>
					</xsl:element>
				</fo:flow>
			</fo:page-sequence>
		</fo:root>
	</xsl:template>
		
	<xsl:template match="ws:p">
		<xsl:apply-templates select="ws:tab[1]"
mode="tab-handle"/>
		<xsl:apply-templates/>
	</xsl:template>
				
	<xsl:template match="ws:b">
		<xsl:element name="fo:inline">
			<xsl:attribute
name="font-weight"><xsl:text>bold</xsl:text></xsl:attribute>
			<xsl:apply-templates/>
		</xsl:element>
	</xsl:template>
	
	<xsl:template match="ws:i">
		<xsl:element name="fo:inline">
			<xsl:attribute
name="font-style"><xsl:text>italic</xsl:text></xsl:attribute>
			<xsl:apply-templates/>
		</xsl:element>
	</xsl:template>
	
	
	<xsl:template match="ws:tab" mode="tab-handle">
			<xsl:apply-templates
select="following-sibling::ws:br[1]" mode="tab-handle"/>
	</xsl:template>
	
	<xsl:template match="ws:br" mode="tab-handle">
		<xsl:variable name="number-of-columns">
			<xsl:value-of
select="count(preceding-sibling::ws:tab)"/>
		</xsl:variable>
		<xsl:element name="fo:table">
			<xsl:attribute name="width">
				<xsl:text>100%</xsl:text>
			</xsl:attribute>
		</xsl:element>
		<xsl:for-each select="preceding-sibling::ws:tab">
		<!-- Note the "first" preceding-sibling tab corresponds
to the 		LAST fixed column in the table -->
		<!-- Formula: actual-column-number = # of
preceding-sibling tabs 		minus (position() - 1) -->
		  <xsl:variable name="column-number"
select="$number-of-columns - (position() - 1)"/>
		  <xsl:variable name="column-width">
				<!-- I want the $column-numberth item
from the parent::p/@tabs, minus the ($column-number - 1)th item - how
can I get that?? -->
			</xsl:variable>
			<fo:table-column
column-number="{$column-number}" width="${column-width}"/>
		</xsl:for-each>
		<!-- here I figure out the width of the final
column...-->
		<!-- but I can do that later. -->
	</xsl:template>
	
	<xsl:template match="ws:br">
		<!-- regular br tag -- empty block -->
		<fo:block/>
	</xsl:template>

</xsl:stylesheet>

As you might notice, my problem comes when trying to compute the width
of the table columns.  I have a formula for it, 

<!-- I want the $column-numberth item from the parent::p/@tabs, minus
the ($column-number - 1)th item - how can I get that?? -->

but can't figure out how to process the p/@tabs element to get the right
value for each column.  For column n I want the nth item - the (n-1)th
item.

Many thanks in advance for any help you can provide.

Sincerely,
Kyle Partridge


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