[Zope-dev] Re: [Zope] Header information on file upload

Florent Guillaume wrote:

The File and Image objects use the Content-Type header on upload if it is provided by the browser. Only if none is provided does it guess one. See OFS.Image.File._get_content_type().

What brings me directly to the central question: Is this Content-Type header provided reliably by every browser? Or: How often must the fallback behaviour be used? Thanks for answers! Martin