315x5x5 obviously means 315 pounds times five reps times five sets. Writing 315x5x5 to mean 315 pounds times five sets times five reps...quite frankly, disgusts me. If you do that, you might as well not even train.
Also, I'm too lazy to find it now in my phone but the "notation thread to end all notation threads," started a couple years ago by Mr. Josiah Moye, IIRC, was pretty fun.