The primary function of either is to emphasize the perfect indifference of the two (or more) things or courses ... ; but a secondary function is to emphasize the mutual exclusiveness, = either of the two, but not both.
12|07|2014 tba, Berlin
25|07|2014 tba, Wien
26|07|2014 tba, Berlin
22|08|2014 Love Techno Hate Germany // about:blank
ZGK @ Scharni Berlin