What does the "ST" code on the boarding passes mean? When I was silver or gold it always said "Gold/ST1" or "Silver/ST1". I always assumed that this was for SkyTeam Elite versus Elite Plus. So when I made Platinum, I was surprised to see "Platinum/ST1". To make things even weirder, it seems that some of my boarding passes say ST1 and others are now saying "Platinum/ST2". Any ideas, or should I find something more important to worry about?