In the MMORPG "Eve Online", a corporation (group of players) can have a NBSI policy. Allys show up as blue, enemies show up as red. However, non-rated people show up without a color. An NBSI policy would mean that all red and non-color (usually strangers) will be shot on sight.
A corporation that does not have an NBSI policy is friendly to all strangers until rated otherwise.