Customs and foreign trade

La déclaration en détail is not a declaration made in detail, and reading it that way is the easiest mistake on this page. « In detail » in English means at length, thoroughly, leaving nothing out. The French en détail is older and far more concrete: le détail is a cutting into pieces, from détailler, to cut up, and in trade it has meant piece by piece for centuries. That is why vendre au détail is to sell retail and stands against vendre en gros, to sell wholesale — nothing to do with how carefully anyone describes anything. So la déclaration en détail is the one that names each consignment item by item, every article with its own code and its own value, as against the déclaration sommaire lodged when the goods turn up. English owns the same root without noticing it: « retail » came from an Old French verb for cutting back, and « tailor » is simply the man who cuts. Read en détail as « item by item » and the customs form makes sense at once; read it as « at length » and it sounds like advice about being thorough.