So I have two questions:
Is setting type="text/plain" supposed to indicate to the UA to display the contents as plain text?
If so, is there a workaround for IE? (I'd rather not take a copy of the file, and give it a .txt extension.)
In my experience it seems as if IE in many cases don't care about the content-type instead relying upon analysing what is received. I've had this issue with some php-generated *.jpgs that were sent with content-type text/plain. Mozilla et al displayed these as text while IE displayed them as a pictures. The special thing about these pictures was that they didn't have any *.jpg-suffix, so no clue was presented to the browser as to the correct filetype except by analysing the stream.