Thanks Casey,

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can I delete the original document and keep only the catalogued 'brain'?

[...]

You could not get rid of the object entirely though, >unless you created a traversal hook in the Documents >object which pretended to make it exist. This is probably more trouble then it is worth though.

OK, I won't go there. I mainly wanted to prevent users from displaying the originals: I'm not Google yet ;-) For now I have removed any references to the DocumentFiles, so the problem is dealt with, but I am still wondering: Where is the index_html method of a DocumentFile, so I could maybe change it to a redirect? Thanks, Ken