Keane JA explained in David Deane & Associates Pty Ltd, how an option or contract relating to the sale of property may, by mutual resolution of the contingencies to which it was previously subject, become properly characterised as a contract of sale. In the present case, even if the option deeds could only be characterised as contracts of sale upon the fulfilment of the contingent conditions to which they were subject, the option deeds are, nevertheless, in my view properly characterised as contracts for the sale of residential property. Although contingent on the exercise of the put and call options granted under the deeds, the applicant assumed obligations to sell and the respondents assumed obligations to purchase from which they could not withdraw. The form and substance of the contracts resulting from the exercise of the options, including the sale price, fell to be determined by reference to the option deeds. The option deeds thus contained the machinery provisions which were facultative of the realization of the lots by sale by the applicant to the respondents. Further, as Barwick CJ observed in Petelin v Deger Investments Pty Ltd, a clause in an option requiring a new contractual document in an identified form to be signed or exchanged does not contemplate the formation of a new and different contract, but merely the recording in a formal fashion of the agreement which resulted from the exercised option.