Not the language. Not really. Do you speak grammar? Do you know technical grammatical terms like “indirect complement” and “predicative adjunct?”
If you’re like most of my clients, you don’t. You’re educated, certainly, and you can string words together in a fashion that makes sense (grammatically) and likely is entertaining for readers, but those terms mean nothing to you. (Here’s where I insert the disclaimer: Those of you among my readership here who are grammarians are not included in the “you” I’m using. You grammarians know these terms. This ain’t about you, as the saying goes.)
And that’s perfectly all right. They don’t have to mean anything to you. I’m the one who needs to know about them, because I’m the editor. I study grammar and syntax (and vocabulary and mechanics and and and), and I know what they mean, and that’s as it should be.
My job is to make your writing sparkle. I don’t need you to know terms you have no reason to know. I need you, my client, to be able to write reasonably well. I’m not here to teach you English. I’m here to help you perfect your writing so your readers will be entertained (not necessarily amused, though, unless you’re intending them to be). And to do that, I need to be able to explain what things like an indirect complement or a predicative adjunct are, in plain language, to you, my client, in order to help you.
For example, let’s take that indirect complement. A complement is a type of dependent. That also means nothing to you. Are you beginning to see why I don’t use this terminology when I’m talking to clients? There’s an awful lot of backstory, as it were. I’ll cut to the chase. In the phrase “a shorter skirt than the dress code permitted,” the phrase beginning with “than” is part of the noun phrase (the words relating to “skirt”), but it’s related to (“licensed by” is the actual terminology) “shorter,” not to “skirt.” “Skirt” is the head of the noun phrase. The complement “than the dress code permitted” isn’t licensed by “skirt,” but by “shorter.” The sense is “shorter than the dress code permitted,” not “skirt than the dress code permitted.” The complement is indirect because it’s not licensed by the head of the phrase.
Do you, the writer, need to know that? NEED to know it? Nope. You don’t. And I don’t need to have to use those terms to tell you what’s amiss with your writing. I need to use plain words, clear language, to communicate with you. So, unless I know you’re a grammarian (or would like to learn this arcane stuff), I won’t speak to you as if you were one.
Have I ever had to explain such a thing to a client? Yep. I don’t have an example to hand, but believe me: every now and again, someone writes something that’s just not grammatically correct, and once I’ve pulled it apart and put it back together, I realize that what they did wrong needs to be explained, so they won’t do it again. Sometimes it takes me upwards of a quarter of an hour (or longer) to figure out what’s wrong. Clients can be very creative in their mistakes. (I’d hope so. They’re writers. They have to be creative.)
[If you want to learn about this arcane stuff, I’ll recommend Huddleston and Pullum’s A Student’s Introduction to English Grammar from Cambridge Press, or the Oxford English Grammar by Greenbaum. The first is more affordable for the casual student.]