1939 JANUARY 24: MANILA CIRCULATING
Department of Labor official mail franked with 6c la Filipina and 10c Fort Santiago O.B. issues mixed with 2c Rizal for proper 18c Single First Class Domestic Registered rate. 
USED DURING THE JAPANESE OCCUPATION PERIOD
1942 NOVEMBER 19: MANILA CIRCULATING
Philippine Executive Commission - Weather Bureau official mail with 6c Pictorial O.B. issue of 1935 for the 5c First Class Letter Rate (1c over paid), 20 grams maximum weight. Properly censored.

Prior to the issuance of Japanese Occupation period official stamps in April 1943, government official mail usually franked with the 5c on 6c La Filipina Provisional issue with "KoYo K.P." marking, either handstamped or manuscript written.

Extremely Scarce and Unusual Usage During the Japanese Occupation Period