Options before

I am concerned about always including the X-Put-Default-Position header. How would you distinguish between a PUT request that is merely updating some properties unrelated to position (with no options.beforeId specified), and an explicit move to the bottom? I should think this should only be included if it is new object with no beforeId (!hasId or options.overwrite === false), or if beforeId === null. And since this header is the conditional actualization of the default position, should it just be X-Put-Position?