Patterned street markings for the blind

Whoa! I had no idea that the gridded dot patterns guiding the blind had different patterns for different situations. Like the idiot that I am, I just assumed that the dotted patterns themselves were the indication to a blind person that they should be cautious while coming upon them. While yes, that is true, the dotted patterns are just one of many different patterns I now know to mean different things to somebody who can't see. Things like bike paths, or tram stops, or train stations, or crosswalks. So interesting!