Example: A sentence like: "This paragraph contains ten errors—both in grammar and format." Does that sentence mean there are ten grammatical errors, and ten formatting errors? Or does it mean there is some combination of the two, totaling ten errors? If you change "both" to "either," does that mean you have ten errors, but all ten are either grammar or formatting? I'm looking for the precise way to indicate there is a combination of the two.
I would change it to This paragraph contains ten errors, in both grammar and format. But for some reason I trip on "ten". I'd be just fine with: This paragraph contains several errors, in both grammar and format. I think that my issue is that "several" leaves the numbers uncertain, while with "ten", I don't know if there are a total of ten errors, some in grammar and some in format, or if there are exactly ten grammar errors and ten format errors, or if there are ten errors that are each both a grammar and a format error. It seems that the first explanation is the right one, but there's still some ambiguity, due to the structure. Edited to add: Oh. I answered your question with your question. OK, my rewrite would be: This paragraph contains ten errors, some in grammar and some in format.
The way you currently have it written, there is a numerical mismatch. The first half says there are ten errors; the second half says there are two errors, each of those two errors being a combination of grammar and format. If you are looking to change the wording as little as possible and get the right meaning, the suggestion given by @ChickenFreak resolves the issue. Simply flip in and both as shown above.
Your example is 100 percent correct. I think it means that all of the ten errors are either one of those two. There's no way to know the breakdown without more information. This sounds like some feedback you got, maybe?
