[Zope] mime types

Hello Zopers, I have some .swf files got into my Zope db via ftp and their mime type has been set by Zope to "application/octet-stream" while it should be "application/x-shockwave-flash" I reset them manually bur how can I edit the associations between the file name extensions and the Zope mime types so that Zope automagically sets the correct value? Thanks anyone will help me Catonano