Some airlines (for example American Airlines) ask for "country of residence" during the booking process. However, the word "residence" has many different definitions in different contexts (i.e. immigration vs. de facto). During the booking process, what definition do airlines expect you to use? Should this be the place you are a legal permanent resident of? Or should it be the place you currently live, temporarily? Does this box have immigration implications or is it just to verify travelers' identity upon check-in?
(In particular, I'm wondering how a US nonresident alien who lives in the US should answer this question. But I want a general answer rather than that specific situation.)