Re: XPATH: get not repeated nodes

But since you haven't said what the input file looks like, or what
output you expect, or what output you got, it's impossible to do
anything other than make blind guesses.

<?xml version="1.0" encoding="ISO-8859-1"?>
<DATOS>
<VERSIONES>
 <V14 cod="1CA8A5H7P5..9X" lit="VERSION1" ord="0000000">
   <V16 cod="1CA8A5H7P5019X20" as="20">
     <VEH codcol="3Y" codtap="Z6FL" tap="Z6FL"/>
     <VEH codcol="5K" codtap="Z6FL" tap="Z6FL"/>
   </V16>
 </V14>
 <V14 cod="1CA8ADH7P5..A0" lit="VERSION2" ord="2">
   <V16 cod="1CA8ADH7P501A032" as="32">
     <VEH codcol="KQ" codtap="Z2FT" tap="Z2FT"/>
     <VEH codcol="5U" codtap="Z2FT" tap="Z2FT"/>
     <VEH codcol="3Y" codtap="Z2FT" tap="Z2FT"/>
   </V16>
   <V16 cod="1CA8ADH7P501A031" as="31">
     <VEH codcol="5U" codtap="Z2FT" tap="Z2FT"/>
     <VEH codcol="3Y" codtap="Z2FT" tap="Z2FT"/>
   </V16>
   <V16 cod="1CA8ADH7P501A030" as="30">
     <VEH codcol="3Y" codtap="Z2FZ" tap="Z2FZ"/>
     <VEH codcol="3Y" codtap="Z2FT" tap="Z2FT"/>
   </V16>
 </V14>
 <V14 cod="1CA8A5J6P5..A0" lit="VERSION3" ord="2">
   <V16 cod="1CA8A5J6P501A031" as="31">
     <VEH codcol="ZR" codtap="Z2FT" tap="Z2FT"/>
     <VEH codcol="4A" codtap="Z2FT" tap="Z2FT"/>
     <VEH codcol="3Y" codtap="Z2FT" tap="Z2FT"/>
   </V16>
   <V16 cod="1CA8A5J6P501A030" as="30">
     <VEH codcol="ZR" codtap="Z2FZ" tap="Sirius Gris Arm.Bito"/>
     <VEH codcol="ZR" codtap="Z2FT" tap="Z2FT"/>
   </V16>
   <V16 cod="1CA8A5J6P501A020" as="20">
     <VEH codcol="KQ" codtap="Z2FZ" tap="Z2FZ"/>
     <VEH codcol="7Z" codtap="Z2FG" tap="Z2FG"/>
     <VEH codcol="5K" codtap="Z2FL" tap="Z2FL"/>
   </V16>
 </V14>
</VERSIONES>
<COLORES>
 <COL cod="3H" lit="Azul Grand Pavois"/>
 <COL cod="3Y" lit="Azul Lucia"/>
 <COL cod="4A" lit="Grilyne"/>
 <COL cod="5K" lit="Azul Mauritius"/>
 <COL cod="5U" lit="Azul Oriental"/>
 <COL cod="7Z" lit="Verde Hurlevent"/>
 <COL cod="8Y" lit="Verde Lenz"/>
 <COL cod="C1" lit="Amarillo Heliodoro"/>
 <COL cod="KQ" lit="Rojo Lucifer"/>
 <COL cod="WP" lit="Blanco Banquise"/>
 <COL cod="X9" lit="Rojo Ardent"/>
 <COL cod="XY" lit="Negro Onyx"/>
 <COL cod="YT" lit="Gris Orageux"/>
 <COL cod="ZR" lit="Gris Aluminio"/>
</COLORES>
</DATOS>

I'll note that in
//V14[cod='1CA8ADH7P5..A0']/V16/VEH[not(@tap=preceding::VEH/@tap)]

you are checking _all_ preceding VEH/@tap attributes, not just those
contained within the specified V14 elements. that may or may not be what
you want to do.

--
//V14[cod='1CA8ADH7P5..A0']/V16/VEH[not(@tap=preceding::V14[cod='1CA8ADH7P5..A0']/V16/VEH/@tap)]
-- //V14[cod='1CA8ADH7P5..A0']/V16/VEH[not(@tap=preceding::VEH/@tap)]

This sounds like a grouping problem (based on the subject line)  so you
may want to check the faq and jeni's site for grouping hints.