--- a/a2n.xsl	Thu Apr 13 23:09:58 2017 +0100
+++ b/a2n.xsl	Tue Apr 25 12:24:31 2017 +0100
@@ -1,13 +1,42 @@
 <?xml version='1.0'?>
 <!DOCTYPE xsl:stylesheet SYSTEM "file:///C:/C64/home/ht/lib/xml/xsl.dtd" >
-<xsl:stylesheet xmlns:e="http://markup.co.uk/excel" xmlns:xs="http://www.w3.org/2001/XMLSchema" version="3.0">
-  <xsl:function name="e:a2n" as="xs:integer">
+<xsl:stylesheet xmlns:e="http://markup.co.uk/excel" xmlns:xs="http://www.w3.org/2001/XMLSchema" version="3.0" xmlns:xpf="http://www.w3.org/2005/xpath-functions" exclude-result-prefixes="e xpf xs" xmlns="http://markup.co.uk/excel">
+
+ <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 -->
-  <xsl:param name="aa" as="xs:string"/>
+  <xsl:param name="aa" as="xs:string" required="yes"/>
+ <xsl:variable name="codeBase" select="string-to-codepoints('A')-1"/>
   <xsl:value-of select="let $l := string-length($aa),
                         $lv := string-to-codepoints(substring($aa,$l))-$codeBase
                         return if ($l=1) then $lv
                                else $lv+(26*e:a2n(substring($aa,1,$l - 1)))"/>
  </xsl:function>
+ 
+ <xsl:function name="e:cr" as="element(e:s)">
+  <!-- Parse a single cell reference into left and right halves,
+       either e:a(bsolute) or e:r(elocatable) -->
+  <xsl:param name="ref" as="xs:string" required="yes"/>
+  <xsl:param name="row" as="xs:integer" required="yes"/>
+  <xsl:param name="col" as="xs:integer" required="yes"/>
+  <xsl:variable name="cr" select="analyze-string($ref,'([$]?)([A-Z]+)([$]?)([0-9]+)')"/>
+  <xsl:variable name="c" select="if ($cr//xpf:group[@nr=1][text()]) then 'a' else 'r'"/>
+  <xsl:variable name="cv" select="e:a2n($cr//xpf:group[@nr=2])"/>
+  <xsl:variable name="r" select="if ($cr//xpf:group[@nr=3][text()]) then 'a' else 'r'"/>
+  <xsl:variable name="rv" select="xs:integer($cr//xpf:group[@nr=4])"/>
+  <s r="{$ref}">
+   <xsl:element name="{$c}" namespace="http://markup.co.uk/excel">
+    <xsl:if test="$c='r'">
+     <xsl:attribute name="d"><xsl:value-of select="$cv - $col"/></xsl:attribute>
+    </xsl:if>
+    <xsl:value-of select="$cv"/>
+   </xsl:element>
+   <xsl:element name="{$r}" namespace="http://markup.co.uk/excel">
+    <xsl:if test="$r='r'">
+     <xsl:attribute name="d"><xsl:value-of select="$rv - $row"/></xsl:attribute>
+    </xsl:if>
+    <xsl:value-of select="$rv"/>
+   </xsl:element>
+  </s>  
+ </xsl:function>
 </xsl:stylesheet>