That is the standard JIC wiring diagram symbology for selector switches. JIC standards have gone by the wayside I guess.Really poor way of doing it. Should be labeled "3SS A, B, C with a note that says it's shown in the open position. If that's really what they are trying to say.
What do the three arrows mean??
I agree for control circuits, but in switchgear (e.g. utility equipment) circuits it was not uncommon to find the OP's style. Another variation is to have the OP's X's all on one side , under the position arrows, which was easier to read for switches with more than 2 operating positions, kind of like a truth table.I have most often seen it as a series of "x" and "o", with "x" for closed an "o" for open. Next to a contact of a 3 position selector switch contact that is closed with the selector in the left position, it would be "xoo" and next to the a contact that is closed in the right position it would be "oox". I have never seen what is shown in this drawing.