In some cases, an appeal to "trade usage" can resolve an ambiguity in a term.
The "trade usage" of a term is a use that is sufficiently regular in a particular type of contractual setting that a party to such a contract is justified in expecting that the other party is using the term in the established way.
By way of illustration, imagine you are in the book printing and binding business. A customer comes to you and asks you for a price quote for printing and binding a two-volume work. You quote a cost "per copy." Assume that, in the book printing and binding business, the regular, well-established practice is for "per copy" in a price quote to mean a single volume. Any experienced person in the business, or who deals with the business, is aware of this fact.
True or False - The trade usage of copy in a price quote in the book printing and binding business is for "per copy" to mean a single volume.