Oh god what is with those em dashes (—) and spacing? Is "foo—bar baz—quux" correctly spaced? Because it took me a minute to parse the title (and the same line in the article). For a while I was thinking that "qualifies—or" and "adverbs—an" are some advanced concepts from linguistic equivalent of algebra. But it turns out that the sentence is just "qualifies, or adverbs, an adverb".