3DS Tag Mode functions called 'SpotPass' and 'StreetPass' in the West

We know them by the catchy names "Itsu no Ma Tsuushin" and "Surechigai Tsuushin," but an English-language hardware outline for the 3DS (PDF) provides the English names for these Tag Mode services, both of which allow the 3DS to communicate wirelessly without the user's involvement.

The ability for the 3DS to seek wi-fi signals while sleeping, and automatically download content, is known as "SpotPass," while the passive communication between DS systems (used, for example, to trade Miis in the new Mii Plaza) is "StreetPass." "It is possible to transmit data for multiple games simultaneously," the document notes.