Oh. OK. That makes sense. And, I guess it follows the Metadata Working Group guidance, as far as it goes.
I agree that writing to Exif is a slippery slope. It just doesn't seem quite right somehow.
But ------ Wherever an application may read IPTC information, in my opinion, it's important to write it consistently to all the data blocks. Otherwise, we end up with a file with out-of-sync data. The three fields in Exif may continue to say "Sam", while the IIM and XMP fields may (presumably correctly) say "Joe". Then a user of software that (stupidly, in my opinion, but arguably in compliance with the MWG guidelines - sheesh) reads exclusively or prefers the Exif will see incorrect data.
And we all know that the software that does that happens to be the most common desktop software in the world. Which doesn't make me happy at all. My sympathies are totally with you. But it is what it is.
So, IMHO, I think you should overwrite those fields with whatever the user leaves or puts in them when they edit in Photo Mechanic.
-Carl
