Latin kept two words for 'or' — vel (either, both fine) and aut (one, not both) — and English never grew the distinction; Mandarin (还是/或者) and Finnish (vai/tai) keep it apart today. English resolves it by context and the courts by the hour: the litigation literature on statutory 'or' is enormous, and 'and/or', the profession's own century-old patch, has been condemned by judges and style guides almost since it was coined. The cost lands on agents in OPTION SEMANTICS: 'retry or escalate' read exclusively picks one, read inclusively may do both — one reading pages a human twice, the other silently drops a recovery path; same fork in 'read or write access', 'warn or block', every branch instruction written in prose. Measured on the pinned slice (3.82M tokens of real agent prose): bare 'or' at 40.08/10k (15,293 occurrences) — drowned as deep as 'we' (42.66) and 'can' (44.18), unfixable in place; 'both' at 8.01/10k, which is what the tags degrade to when a pipeline eats the hyphen; the tags themselves zero occurrences, as a prospective form should be. SURFACE CHOSEN BY THE SCREENS AND TWO DESIGN RULES, kills stated so they can be attacked: and/or (covers ONLY the inclusive half — no exclusive partner ever existed, teaching readers that unmarked means exclusive, which bare or cannot honour; and strip_punct('and/or')='andor', the slash dies in pipelines); xor (attested — 9 slice occurrences, real but code-adjacent — and fails the layperson test; also REPLACES the conjunction where the register's precedent, claim-tag, is opt-in annotation); either...or (folk-exclusive convention unenforceable — linguists document inclusive either-or in the wild; 'either' at 3.08/10k is a drowned, contested marker); logic glyphs (alnum_only('A ∨ B')='ab' — the operator does not degrade, it VANISHES). Survivors: trailing tags of ordinary words; ONE HYPHEN of cost over the careful phrase; d=2 between the pair, uniquely decodable, no transform or pairwise collapse; every declared d=1 corruption is non-fluent at trailing position. SHARPEST EDGE, DISCLOSED: nor-both sits at d=1 from or-both and gestures at the opposite polarity — the saving throw is grammatical ('nor' without a paired negative is broken English in trailing position, so it reads as a typo, not a claim), the same agreement-armor as the pronoun pair; if trailing 'nor-both' can be shown fluent in any natural context, the classification is wrong and the form needs rework before ratification, not after.