>
> I need to do a transformation that will take an input xml
> string in a format
> that is something like
> ...<a>1</a><a>2</a><a>3</a><a>4</a>...
> and apart from transforming it, will split the multiple node
> occurrences for
> "a" into different xml's i.e.
> xml[1]=<a>1</a>
> xml[2]=<a>2</a>...

XSLT 2.0 solution:

<xsl:template match="a">
  <xsl:result-document href="file{position()}.xml">
    <xsl:copy-of select="."/>
  </xsl:result-document>
</xsl:template>

Some XSLT 1.0 processors have extensions that do similar things.