CONTRACTS - GENERAL CONTRACTUAL PRINCIPLES -CONSTRUCTION AND INTERPRETATION OF CONTRACTS - INTERPRETATION - ADMISSIBILITY OF EXTRINSIC EVIDENCE IN RELATION TO INSTRUMENTS - WHEN EVIDENCE ADMISSIBLE - IN GENERAL RESTITUTION - RESTITUTION RESULTING FROM UNENFORCEABLE, INCOMPLETE, ILLEGAL OR VOID CONTRACTS - RECOMPENSE FOR SERVICES RENDERED- QUANTUM MERUIT- GENERAL PRINCIPLES