Cheers,
Abel

   <xsl:template match="/shipment" >
       <xsl:apply-templates select="header" />
       <xsl:apply-templates select="detail" />
       <xsl:apply-templates select="detail/containers/box" />
   </xsl:template>

   <xsl:template match="header">
       <xsl:text>REC1*</xsl:text>
       <xsl:value-of select="shipmentId"/>
       <xsl:text>&#xA;</xsl:text>
   </xsl:template>

   <xsl:template match="po" >
       <xsl:text>*</xsl:text>
       <xsl:value-of select="."/>
       <xsl:if test="position() mod 2 = 0 or position() = last()">
           <xsl:text>&#xA;</xsl:text>
       </xsl:if>
   </xsl:template>

I need to take the following XML document (a shipping delivery) and
output as a fixed length file.  The fixed length file has expected
repetitions within it, as follows:
1) The first output record -- REC1 -- is the shipping header.
2) The second output line(s) -- REC2 --are the purchase order(s). Each
line of text will contain least one and up to two purchase orders.
3) The final output line(s) --REC3 -- are the containers. Each line of
text will contain at least one and up to four containers.