It could've been, and should've been, worse

I'm taking an accounting class, and one part of it is really bothering me. I'm no punctuarian, I'm pretty bad at most rules, and terrible at memorizing. But I feel very sure that this is totally incorrect.

In accounting, it's considered correct to abbreviate "Financial Statement" F/S, "Balance Sheet" B/S, Porter and Norton "P/N", and etc. Is the slash ("/") not considered to stand in for the word or? Are we not actually saying, Balance Or Sheet, and Financial Or Statement? Shouldn't we actually, if any punctuation is necessary, use the dash, a symbol of the compound word? F-S; B-S. Of course, Balance Sheet is not a compound word. It's two words that go together. A compound word is two words that are stuck together. There's a difference. I am sure that we should actually say "FS" and "BS", just like we say CFO instead of Cash Flow from Operations.

Any help in this matter would be appreciated