> Saying black is specific but person of color just means not white

Is Obama black or white?

As a father to a mixed race son, where people draw the line on whether it's "OK" for someone to self-identify or be described as black vs. white is a topic that interests me, and it's wildly inconsistent (but leaning strongly towards it taking far more white ancestry for most people to "accept" that people call themselves white than the reverse), and highly politicised, and there are absolutely no clear lines.

EDIT: I've spoken to my son about answering the inevitable "but where are you really from originally" with "Norway" for example, if he feels safe doing so (and safety is a real concern with that), since I'm Norwegian. It's just as accurate as answering Nigerian (his mother is Nigerian), which would be the answer most people asking that question would be looking for, but would hopefully make at least some people stop to think why they were asking it.

Which, sorry but, makes it a very dubious expression because it seems to be definitory of a narrow set opposed to a wealth of difference. Suppose you were Italian (a "Macedonia" of mixed blood since the ancient times, where the heterogeneity in physical traits is pretty high, but without a sense of "tribal" difference within that broad set): it would appear to make more sense to use the term "white" for the most eburneous sun-threatened Irish, than to say "white versus coloured" for people that already show very varied in their looks - in their """shades""", if you wish.

Is it used more broadly though? I've never heard it (self-describingly) from anyone of (East/West/incl. Indian subc.) Asian descent for example.

That means nothing.

Who is "white" has changed throughout history.