In linguistic theory—in contrast to previous linguistic science and in conscious reaction against it—we strive for an unambiguous terminology. But in few places does the linguistic theoretician find himself in such terminological difficulties as here. We have tentatively called the both-and function a conjunction (with reference to the terminology of logic) or a coexistence, and the either-or function a disjunction (also with reference to logical terminology) or an alternation. But it will be certainly inexpedient to retain these designations. Linguists are accustomed to understanding by a conjunction something quite different, and we are forced in agreement with tradition to use conjunction in a corresponding fashion (for a so-called “part of speech,” even if we do not think it possible to define it as such). Disjunction has been used fairly widely in recent linguistic science as a specific kind of either-or function, and it would cause confusion and misunderstanding if we introduced the same term as a general designation of all either-or functions. Alternation, finally, is a deep-rooted and certainly ineradicable (moreover a convenient) linguistic name for a very specific kind of function (notably, the so-called ablaut and umlaut), which has strong associations with the either-or function and in reality is an especially complicated either-or function; it will therefore not do to introduce alternation as a general name for either-or functions. The term coexistence, it is true, has not been appropriated, but we do not recommend it because, among other reasons, a widespread linguistic usage connects it in a certain sense with coexistence between members of a paradigm.
Why use these words in laying out the relationships if you don't recommend using them? >.>
This feels very much like a logic book rather than a linguistic/semiotic book (of course, they're similar). It kind of feels like definition vomit. Like it hasn't been too too hard to follow yet, but I worry.
Also, amusingly, D&G don't have the same reservations about terms overlapping with other fields as hjelmslev does. They use disjunction and conjunction x3