2006.08.24 17:45 "Re: [Tiff] IPTC tag", by Phil Harvey
My 2 cents:
I have found at least one utility (Nikon Capture) that won't read IPTC information unless the format LONG, and as you mentioned this is the way it is written by Adobe. So I don't think any IPTC support would be very useful unless it reads and writes as LONG too.
Also, I don't see why you can't accept any data type too (SHORT, etc), and let the IPTC parser determine if it is valid IPTC or not.
For what it's worth, this sort of thing happens on a fairly regular basis in IFD-formatted makernote information. If anyone eventually wants use libTIFF to read/write maker note information, it may be worthwhile to add the ability to read and write data in a specific format that is different from the format tag written in the IFD. This is how ExifTool handles it, and this solves the problem of the strange IPTC data type.