The Institute Cargo Clauses are a set oftermsforcargo insurancepoliciesvoluntarily adopted asstandardterms by many internationalmarine insuranceorganizations, including the Institute Of LondonUnderwritersand the American Institute Of Marine Underwriters. Widestinsurancecoveris provided under ‘InstituteCargoClause A’, a more restrictive cover under ‘Institute Cargo ClauseB’, and the most restrictive cover under ‘Institute Cargo Clause C.’

Source  http://www.jus.uio.no/lm/institute.marine.cargo.clauses.a.1982/doc.html#1

Clause A is sometimes referred to as “Full Cover” or “All Risk”, Clause B as “With Particular Average”, and Clause C as “Free of Particular Average”.

Term Definition
Insurance, All-risk This type of insurance offers the shipper the broadest coverage available, covering against all losses that may occur in transit.
Insurance, General-Average In water transportation, the deliberate sacrifice of cargo to make the vessel safe for the remaining cargo.Those sharing in the spared cargo proportionately cover the loss.
Insurance, Particular Average A Marine insurance term to refer to partial loss on an individual shipment from one of the perils insured against, regardless of the balance of the cargo. Particular-average insurance can usually be obtained, but the loss must be in excess of a certain percentage of the insured value of the shipment, usually three to five percent, before a claim will be allowed by the company.

Source http://www.scl.gatech.edu/resources/glossary/?fuseaction=glossary.main&letter=i
Source http://cig.unjlc.org/library/customs-glossary