At an event the positions will be determined by the event sailing instructions and ties will be split in accordance with the RRS.
The traveler series SI.'s also include a line to say that ties will be split in accrdance with RRS A 8 or whatever.
This means that the tie will first be split on the number of 1sts, 2nds, 3rds etc, then if there is still a tie the position in the last race and I can't remember the 3rd option.
The S.I.s reffer to the RRS to keep them consise. I wouldn't expect everyone to know the full RRS word for word, i don't , but it should be possible for anyone to find the part referenced.