--- a/rect.xsl	Tue Apr 04 16:20:46 2017 +0100
+++ b/rect.xsl	Tue Apr 04 17:45:50 2017 +0100
@@ -3,6 +3,10 @@
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="3.0" xmlns:s="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:e="http://markup.co.uk/excel" exclude-result-prefixes="xs s xpf" xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:xpf="http://www.w3.org/2005/xpath-functions">
  <xsl:strip-space elements="s:sheetData"/>
  
+ <xsl:variable name="refs" select="collection()[2]/*"/>
+ 
+ <xsl:key name="ref" match="e:ref" use="@r"/>
+ 
  <xsl:function name="e:a2n" as="xs:integer">
   <!-- Convert an alphabetic excel column 'index' into a number,
        a sort of base 26 + 1, since 'A' is 1 and 'AA' is 27 -->
@@ -51,8 +55,10 @@
        <xsl:variable name="col" select="."/>
        <xsl:variable name="r" select="concat(e:n2a($col),string($row))"/>
        <xsl:variable name="c" select="$cells[@r=$r]"/>
+        <xsl:variable name="reffed" select="key('ref',$r,$refs)"/>
        <e:c c="{$col}">
         <xsl:if test="$c/s:f"><xsl:attribute name="f">1</xsl:attribute></xsl:if>
+        <xsl:if test="$reffed"><xsl:attribute name="r"><xsl:value-of select="$reffed/@c"/></xsl:attribute></xsl:if>
         <xsl:if test="$c/*"><xsl:value-of select="substring($c/@e:type,1,1)"/></xsl:if>
        </e:c>
       </xsl:for-each></xsl:if>