the "SG form"), which parties were at liberty to use if they wished. Because each term in the policy had been tested through at least two centuries of judicial precedent, the policy was extremely thorough. However, it was also expressed in rather archaic terms. In 1991, the London market produced a new standard policy wording known as the MAR 91 form using the Institute Clauses. The MAR form is simply a general statement of insurance; the Institute Clauses are used to set out the detail of the insurance cover. In practice, the policy document usually consists of the MAR form used as a cover, with the Clauses stapled to the inside. Typically, each clause will be stamped, with the stamp overlapping both onto the inside cover and to other clauses; this practice is used to avoid the substitution or removal of clauses. Because marine insurance is typically underwritten on a subscription basis, the MAR form begins: We, the Underwriters, agree to bind ourselves each for his own part and not one for another [...]. In legal terms, liability under the policy is several and not joint, i.e., the underwriters are all liable together, but only for their share or proportion of the risk. If one underwriter should default, the remainder are not liable to pick his share of the claim. Typically, marine insurance is split between the vessels and the cargo. Insurance of the vessels is generally known as "Hull and Machinery" (H&M). A more restricted form of cover is "Total Loss Only" (TLO), generally used as a reinsurance, which only covers the total loss of the vessel and not any partial loss. Cover may be on either a "voyage" or "time" basis. The "voyage" basis covers transit between the ports set out in the policy; the "time" basis covers a period, typically one year, and is more common. Protection and indemnity A marine policy typically covered only three-quarter of the insured's liabilities towards third parties (Institute Time Clauses Hulls 1.10.83). The typical liabilities arise in respect of collision with another ship, known as "running down" (collision with a fixed object is a "allision"), and wreck removal (a wreck may serve to block a harbour, for example). In the 19th century, shipowners banded together in mutual underwriting clubs known as Protection and Indemnity Clubs (P&I), to insure the remaining one-quarter liability amongst themselves. These Clubs are still in existence today