10/21/1937
https://www.presidency.ucsb.edu...
"Executive Order No. 7234 of November 25, 1935, entitled 'Deposit Money Orders Issued by the Canal Zone Postal Service', is hereby revoked."
"Postal-savings certificates issued by the Canal Zone Postal Service shall bear interest at the rate of one-half of one per centum for each period of three full calendar months from the date of issue."
"The provisions of this order shall apply to all outstanding deposit money orders issued by the Canal Zone Postal Service prior to August 13, 1940."
"Interest on all postal-savings certificates shall be payable when the certificates are paid."