Gosh there is so much over-thinking of this process going on here. For a conservator's purposes, yes it is important to record which metals were used in the making of the print, but the viewing (and buying) public either cannot or does not care to tell the difference between the two 99% of the time. While on a sentimental level I agree that there is something to the look of a platinum/palladium print contact printed from an in-camera original negative that is not there with a digitally enlarged negative, and a trained eye can perceive a difference between the two, I really don't think it is worth getting titties in a twist over. Some things will never have been recorded in-camera, like 20x24 inch platinum prints of live action scenes. But if it aesthetically displeases you, you don't buy it, same as you would dogs playing poker on velvet. I don't think you need to label in a sales situation with the same level of detail that an FDA food product label requires - that's something you explain to the customer when they engage you in a discussion about the image, and you can provide as documentation after the purchase is completed. Far too many photographers get hung up on over-explaining the technical details of their work to audiences instead of communicating the why of the image. People buy on the why, not the how. As long as you're honest about how you create your images, I don't see what the big deal is about the how. We're really getting into the level of asking a painter which brand of oil paint he or she uses and which brand of brushes. If I'm buying an oil painting, I do care that it is in fact an oil and not acrylic. And sure it would be cool and impressive to know that the artist grinds her own pigments, but that's not what is going to sell me on the painting.