Martijn
What if I only have one? Is "last" my family name or the name that is written last? Some more questions like that are put forward in the article I linked. I am a stickler for this as I have an easy, ASCII writable, European name and software still messes up capitalisation when they make me put my family name in a separate field.
Asko P.
Having an O in my last/family name makes a lot of software also mess up and use O instead. I don't have a middle name, just first and last, but in case I use one input, how would I know how to split it up into a use case where I need to display "Hello, John!"?
Mark Dain
Full name and Display name? Perhaps with an auto fill of the first word when they setup the account? I'd probably use my handle for display :P