I wouldn't advocate using these abbreviations in a technical document that has safety implications, but in an S-1 it's fine. If you make a mistaken trade becaus

I wouldn't advocate using these abbreviations in a technical document that has safety implications, but in an S-1 it's fine. If you make a mistaken trade because you can't keep your scales straight I don't really have a lot of sympathy. If they don't know the difference in the first place they're not reading this document.