<unit>
  <subunit/>
     <sub-subunit/>
     <sub-sub-subunit/>
</unit>

<unit>
  <subunit>
        <sub-subunit>
               <sub-sub-subunit>
                </sub-sub-subunit>
         </sub-subunit>
  </subunit>
</unit>

I ask myself if it would be possible to be generalized?
Creating a general template that resolve this common problem.
Always is the same, but with different name of tags.

Albert Juhi wrote:
> Hi,
>
> I have been trying the code, and the output it's not that I expect
> because the tag subunit is identet inside another subunit like this
>
> </sub-sub-subunit>
> </sub-subunit>
> </sub-subunit>
> </sub-subunit>
> </sub-subunit>
> </sub-subunit>
> </sub-subunit>

> And there are duplicated nodes

The duplicated nodes could be explained if there are indeed
sub-sub-subunit's that are not preceeded by a matching sub-subunit,

I wrote templates that could point to this case, by showing the
preceeding subunit's:

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

<xsl:template match="unit">
       <xsl:apply-templates select="subunit"/>
</xsl:template>

<xsl:template match="subunit">
       <xsl:apply-templates select="following-sibling::node()[1]"

</xsl:template>

<xsl:template match="node()" mode="check">
       <xsl:apply-templates select="following-sibling::node()[1]"

</xsl:template>

<xsl:template match="sub-sub-subunit" mode="check">
       <xsl:text>&#10;inproper nesting starting with node &#10;</xsl:text>
       <xsl:copy-of select="preceding-sibling::subunit[1]"/>
       <xsl:copy-of select="current()"/>
</xsl:template>

<xsl:template match="sub-subunit" mode="check"/>