“The starting point, in construing an Unless Order, as any other Order, is the ordinary meaning of the words used. The legal and procedural context will always be relevant: for example the context may show that the ordinary meaning cannot have been the meaning in the Order. In any event the party who has to comply with an Order must be able to see from its terms what is required to comply with it; an Order cannot be read expansively against the party who has to comply.”