How do I verify the values that can be used in Format with the IMT scheme?
Only the values registered at: http://www.isi.edu/in-notes/iana/assignments/media-types/media-types are valid for designation as MIME-types. Some examples of incorrect MIME types in format fields that we’ve seen include: text.html (should be text/html) and text/pdf (should be application/pdf). We sometimes also see MIME types that are not on the approved list: Text/Word, Text/Excel, Audio/RealAudio, Video/Flash, Video/RealTime, Video/ShockWave. Because IMT is a controlled vocabulary, terms can’t be concocted (they must go through a process of approval). On the other hand, if the IMT encoding scheme is not used, terms can be from local lists and still be useful, even if they’re not yet on the IMT list.
