1. In this Schedule, unless either the context otherwise requires or the contrary is expressed, the covenantor's liability in respect of any covenant extends to the acts or omissions only of persons within any of the following classes:
(1) the covenantor and any person conveying by the covenantor's direction;
(2) any person through whom the covenantor derives title;
(3) any person (including a mortgagee) who either holds or has held a derivative title from the covenantor for less than the estate or interest vested in the covenantor or who holds or has held such a derivative title from any predecessor in title of the covenantor;
(4) any person who holds or has held in trust for the covenantor.
2. It is not a breach of a covenant contained in this Schedule where the conveyance by the covenantor was made expressly subject to the act, matter or thing which, but for this paragraph, would or might have caused such a breach.
3. The covenantor has no liability for any defec…