using format-alist

[bob . hepple]

I'm trying to read a structured text format (gjots) into emacs org-mode - I 
have converters gjots2org and org2gjots and they do the encoding/decoding as 
filters. 

I had hoped that format-alist would do what I want but it can't use a file 
extension like *.gjots, so I tried this:

    (setq format-alist
          (cons '(gjots "gjots" nil "gjots2org" "org2gjots" t nil) 
format-alist))
    (define-derived-mode gjots-mode org-mode "gjots"
      "Major mode for editing gjots files."
      (call-process-region (point-min) (point-max) "gjots2org" t t) ; convert 
to org-mode
      (set-buffer-modified-p nil)
      (setq buffer-file-format 'gjots)) ; this is supposed to define encoding 
on write!!!

.... to some extent it's working ... but when I save, it's in org-mode format, 
not gjots format.

Anyone got any idea what I'm missing?

Thanks



Bob