The change in the rules relating to the disclosure of documents in litigation was one of the most significant wrought by the CPRs. The change from “discovery” to “disclosure” was not simply a change of name. The so-called Peruvian Guano test,1 which required a party to disclose any documents which might enable another party either to advance his own case or that of his adversary or which might fairly lead to a train of inquiry which might have either of those two consequences, and which was the norm in litigation before 1999, is no longer applicable save in limited circumstances.2 Disclosure on a more limited basis, known as “standard disclosure”, is now the norm in commercial cases, as it is in other courts under the CPRs generally.