dxf images are detected by nautilus as text/plain, unless I change it a sub-class of text/plain in /usr/share/mime/packages/freedesktop.org.xml. Tested with shared-mime-info-0.19. There are both binary and ascii versions of dxf-files, but I don't have any binary files to test with. Maybe two mime types are needed, one for acsii and one for binary Drawing Interchange File? See http://en.wikipedia.org/wiki/AutoCAD_DXF
I've added mime-magic to detect ASCII and binary versions of the files (the only difference between the 2 formats are that some sections might contain binary data for preview). 2007-02-05 Bastien Nocera <hadess@hadess.net> * freedesktop.org.xml.in: Add magic to detect AutoCAD DXF files (Closes: #9472)
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