III. Provisional Sale and Purchase Agreement
Under section 3 of the Conveyancing and Property Ordinance (Cap. 219 of the Laws of Hong Kong), no legal action concerning any contract for sale of land (including house/flat/building) will be enforced by the courts unless the contract is made in writing. In other words, you will lose the protection from the courts if you sell or buy a flat through an oral agreement.
Despite bearing the word "provisional", a duly signed provisional sale and purchase agreement is a legally binding contract that must be fully obeyed by the parties involved. If the formal sale and purchase agreement (which is intended to replace the provisional agreement) cannot be signed, the parties can rely on the provisional agreement to proceed with the deal or to sue for compensation.