For the purposes of this Act—
(a)if an agreement would give rise to a tenancy but for the fact that it does not specify an ish, it is to be regarded as giving rise to a tenancy,
(b)once an agreement has given rise to a private residential tenancy, it is to continue to be regarded as giving rise to a tenancy despite the term of the agreement requiring the tenant to pay rent subsequently being removed from the agreement or otherwise ceasing to have effect.