Unknown Element comment in inline.xsl

Hi,

I found the following template rule in {fo,html}/inline.xsl:

 <xsl:template match="comment[&comment.block.parents;]|
                      remark[&comment.block.parents;]">
 ...

However, there is neither a comment element in DocBook 4 nor in version 5. 
Is there any reason for the comment in the template rule above?


Thanks,
Tom

-- 
Thomas Schraitle