If someone can post here examples of use of variable defined as global,
 assign in one template and  used in another, that will be nice. 

You can not assign a value in one template and use it in another. The
scope of a variable is the element containing the variable binding.

Most likely you don't need a variable at all.

> > <xsl:template match="ObjectIndex">
> >      <xsl:value-of select="@Code"/><xsl:text>;</xsl:text>
> >      <xsl:value-of select="@Description"/><xsl:text>;</xsl:text>
> >      <xsl:copy-of select="$FileExtention" /><xsl:text>|</xsl:text>
> >      <xsl:text>&#xD;&#xA;</xsl:text>
> > </xsl:template>
> >

could be 

 <xsl:template match="ObjectIndex">
      <xsl:value-of select="@Code"/><xsl:text>;</xsl:text>
      <xsl:value-of select="@Description"/><xsl:text>;</xsl:text>
      <xsl:value-of select="../../ObjectFormat/@FileExtention" /><xsl:text>|</xsl:text>
      <xsl:text>&#xD;&#xA;</xsl:text>
 </xsl:template>

but as you did not show your input I had to guess the path 
../../ObjectFormat/@FileExtention
from the ObjectIndex node to the FileExtention node.

David

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