any semantic diff between a file name and directory name?

["Robert P. J. Day" <rpjday@crashcourse.ca>]

   (not strictly a docbook question but i'm interested in the opinion  
of the gurus here.)

   i'm perusing the semantic markup of someone who has created their  
own XML language which, in all, looks fairly similar to docbook, but  
this person has explicitly defined two elements -- "file-name" and  
"directory-name" -- to be used for that respective markup.

   i'm aware that docbook has the standard "filename" element and, as  
a longtime unix/linux user, i'm well aware that directories are simply  
special cases of files and i have always marked up directory names  
with just <filename>.

   so ... would there be any compelling reason to distinguish between  
the two?  i don't have access to the XSLT so i don't know if they're  
really being treated differently and, visually at least, they're both  
just being rendered in identical monospaced font when i generate the  
HTML.

   thoughts?

rday