6. Extensions or renewals of promissory notes brought about by extension of mortgages by which such notes are secured.
7. Instruments in the form of promissory notes, representing the interest upon promissory notes, not included under (6) below, and either separate from or prepared in a form and for the purpose of being separated from the principal note.
8. Policy loan and premium extension agreements containing an unqualified promise to pay a specified sum of money at a certain date, except where the sole remedy of the payee in case of non-payment of the premiums or loans is to reduce or cancel the rights of the insured.
The following instruments are exempt:
1. Certificates of deposit.
2. Bank notes issued for circulation.
3. Promissory notes executed and mailed in Canada to a payee within the United States.
4. Promissory notes issued directly by foreign governments and placed in this country for sale.
5. Promissory notes secured by certificates of indebtedness issued by the Director General of Railroads.
6. Coupons and interest notes which are attached to a principal obligation and are substantially repetitions of the promise to pay interest contained in the principal obligation.