32. Except in the cases mentioned in section 89, every document to be registered under this Act, whether such registration be compulsory or optional, shall be presented,- (a) by some person executing or claiming under the same, or, in the case of a copy of a decree or order, claiming under the decree or order, or (b) by the representative or assign of such person, or (c) by the agent of such person, representative or assign, duly authorized by power-of-attorney executed and authenticated in manner hereinafter mentioned.