If the landlord and the contract-holder under an occupation contract agree to end the contract, the contract ends—
when the contract-holder gives up possession of the dwelling in accordance with the agreement, or
if he or she does not give up possession and a substitute occupation contract is made, immediately before the occupation date of the substitute occupation contract.
An occupation contract is a substitute occupation contract if—
it is made in respect of the same (or substantially the same) dwelling as the original contract, and
a contract-holder under it was also a contract-holder under the original contract.
This section is a fundamental provision which is incorporated as a term of all occupation contracts.