2009.03.04 00:55 "[Tiff] TIFF-FX", by Steve Underwood
I tried the current libtiff 4.0 beta, and found it lacks support for the extra tags defined for TIFF-FX files (RFC3949). I am wondering if that is simply because nobody did the work, or because it was intentionally left out. RFC3949 look a long time to be finalised, and there were patent wrangles between Xerox and Adobe for a while. It looks like that's all sorted out, though, and the IETF seems happy enough to have published RFC3949.
If there is nothing to block the addition of the relevant tags, I will cook up a patch to add support.