RE: preceding-sibling:: while keeping xml well formed

   <xsl:template match="/">
       <data>
           <xsl:apply-templates/>
       </data>
   </xsl:template>

   <xsl:template match="text()[ancestor::i and not(ancestor::b)]">
       <italic>
           <xsl:copy-of select="."/>
       </italic>
   </xsl:template>

   <xsl:template match="text()[ancestor::b[ancestor::i]]">
       <bolditalic>
           <xsl:copy-of select="."/>
       </bolditalic>
   </xsl:template>

<?xml version="1.0" encoding="UTF-8"?>
<data>
 <italic>This</italic>
 <bolditalic>is</bolditalic>
 <italic>valid</italic>
</data>

I am using xslt to convert one xml to another importable xml.
Everything is going fine except for the fact that the program I am
importing into supports <italic>, and <bold>, but needs a <bolditalic>
when the both are together.

My original xml file is used on the web so of course

<i>This<b>is</b>valid</i>.

I assume this can be done using the preceding-sibiling axis to achive
something along the lines of

<italic>This</italic><bolditalic>is</boldItalic><italic>valid</italic>