Earlier quoted context omitted.
I am from India and so I grew up on British English and have stuck to that. I was gifted a Oxford Pocket Dictionary when I was a kid, by an uncle. I practically learned my English with that dictionary, had it till recently when I passed it down to my niece(who is in 5th grade as of now). Now, you'll have to trust me on these two statements: 1. I did learn " sth 'can' be used for something " from that old good little…
Same here in China. I grew up learning English using mostly British textbooks and sth is introduced to us quite early, pretty much like xyz in algebra. I'm actually quite surprised to find out it's perhaps not that common in the US.
I've only ever seen South abbreviated as S, never as sth.