Input XML:
-----------
<OUT>
<OUT_ITEM>
<ITEM_ID>151844</ITEM_ID>
</OUT_ITEM>
<OUT_ITEM>
<ITEM_ID>151845</ITEM_ID>
</OUT_ITEM>
<OUT_ITEM>
<ITEM_ID>151846</ITEM_ID>
</OUT_ITEM>
</OUT>

Expected Output:
----------------
<?xml version = '1.0' encoding = 'UTF-8'?>
<ILResponse>
<DA>
<Revision>
<Number>1</Number>
</Revision>
</DA>
<DA>
<Revision>
<Number>2</Number>
</Revision>
</DA>
<DA>
<Revision>
<Number>3</Number>
</Revision>
</DA>
</ILResponse>

XSL tried code:
---------------
<xsl:template match="/">
<ILResponse>
<xsl:for-each select="OUT/OUT_ITEM">
<DA>
<xsl:variable name="ItemIndex" select="0"/>
<xsl:variable name="ItemIndex1" select="$ItemIndex+1"/>
<Revision>
<Number>
<xsl:value-of select="$ItemIndex1"/>
</Number>
</Revision>
</DA>
</xsl:for-each>
</ILResponse>
</xsl:template>

I want to increment the variable for the no of times the OUT_ITEM are there in the input XML. My goal is to maintain the index value. please suggest. Found that every time the initial value of the variable is returned.