invisible buffer is it possible?

[Phillip Lord <p.lord@russet.org.uk>]

I'm just wondering whether I can create an invisible buffer, or
something similar? That is one which does not appear in the buffer
menu list, and you can't accidentally change to. 

The reason for this is that I have use this little hack....

(add-hook 'xml-mode-hook
          'phil-psgml-hook)
          
(defun phil-psgml-hook()
  "Does various checks and sets up various variables
 1) Checks to see if the file being loaded is one which needs a fake DOCTYPE. 
 That is I don't want to have the doctype in the buffer but want psgml mode to
 think that there is one. 
 2) Sets up default validate command"
  (interactive)
  (if (string= "build.xml"
               (file-name-nondirectory (buffer-file-name)))
      (setq sgml-parent-document '( "~/emacs/anthead.xml" "" "project"
      ))))


What this does is allow me to use a DTD for editing ant build files,
without having to put the doctype declaration into the build file
itself, which goes into the anthead.xml file. 

However it results in the anthead.xml file being opened into a buffer,
and it's just an annoyance. 

Is there someway that I can mark it invisible?


Cheers

Phil