@xrisk before you get to that point, you might first ask for a Thing and then the server tells you "sorry, i can't serve you the thing itself, i can only serve you something related to the thing like a descriptor document" (this is what 303 See Other does)then you ask for the Other and the server tells you "oh i have this Other, but in multiple formats" (this is what 300 Multiple Choices does)using an HTTP Accept header lets you skip the second step but not the first