This is an unofficial version of a Massachusetts General Law.
Section 5-505
As to acts undertaken in good faith reliance thereon, an affidavit executed by the attorney in fact under a power of attorney, durable or otherwise, stating that he did not have at the time of exercise of the power actual knowledge of the termination of the power by revocation or of the principal's death, disability, or incapacity is conclusive proof of the nonrevocation or nontermination of the power at that time. If the exercise of the power of attorney requires execution and delivery of any instrument that is recordable, the affidavit when authenticated for record is likewise recordable. This section shall not affect any provision in a power of attorney for its termination by expiration of time or occurrence of an event other than express revocation or a change in the principal's capacity.