CONTRACTS – GENERAL CONTRACTUAL PRINCIPLES – CONSTRUCTION AND INTERPRETATION OF CONTRACTS – INTERPRETATION OF MISCELLANEOUS CONTRACTS AND OTHER MATTERS – where the parties entered into a long term contract under which the first appellant (“the Supplier”) agreed to supply cement products to the first respondent (“the Purchaser”) – where the contract contained a price adjustment mechanism which allowed the Purchaser to serve a notice on the Supplier containing market pricing evidence – where such a notice would have the effect of reducing the price of products under the contract unless the Supplier elected to suspend supply for six months – where the Purchaser served a notice containing market pricing evidence that consisted of a quotation for supply commencing at a future date, rather than at the date of the notice – whether this was a valid and effective pricing notice under the clauseCONTRACTS – GENERAL CONTRACTUAL PRINCIPLES – CONSTRUCTION AND INTERPRETATION OF CONTRACTS – INTERPRETATION OF MISCELLANEOUS CONTRACTS AND OTHER MATTERS – where, in response to the purported pricing notice served by the Purchaser, the Supplier gave the Purchaser a notice stating that the notice was invalid and referring the matter to the dispute resolution process under the contract – where this notice also stated that if, as the Purchaser contended, the notice was valid, the Supplier elected to suspend supply under the contract – whether the Supplier waived any invalidity in the Purchaser’s notice by its notice electing to suspend supply – whether the Supplier’s notice was effective to suspend supply under the contractCONTRACTS – GENERAL CONTRACTUAL PRINCIPLES – CONSTRUCTION AND INTERPRETATION OF CONTRACTS – INTERPRETATION OF MISCELLANEOUS CONTRACTS AND OTHER MATTERS – where the price adjustment clause provided that if, during a suspension period, the Purchaser ceased to be able to or chose not to procure supply at the price specified in the pricing notice giving rise to the suspension, the Purchaser was obliged to resume purchasing cement products from the Supplier at the prevailing prices under the contract – whether “supply” in this clause referred to supply of the quantity of cement products the Purchaser was obliged to purchase from the Supplier under the Agreement or supply of a lesser quantity set out in the pricing notice – whether any suspension period was brought to an end pursuant to this clauseCONTRACTS – GENERAL CONTRACTUAL PRINCIPLES – CONSTRUCTION AND INTERPRETATION OF CONTRACTS – INTERPRETATION OF MISCELLANEOUS CONTRACTS AND OTHER MATTERS – where the Purchaser gave a further pricing notice during a later suspension period – whether, upon the proper construction of the clause, the Purchaser was permitted to serve a pricing notice during a suspension period – whether the pricing notice was effective to reduce the price under the contract