4c and 10c Definitive Stamps : May 1, 1948
The 4c and 10c definitive stamps were overprinted O.B. (Official Business). The official stamps were issued on May 1, 1948.
First Day Cover
16 cent Definitive Stamp : May 28, 1948
The 16c definitive, overprinted O.B., was issued on May 28, 1948.This was the stamp which incorrectly labelled the Rial Gate as the Santa Lucia gate.
There were 999,896 16 cent official stamps printed , but on July 28, 1950 787, 879 were withdrawn because of the error,. (Source : 1997 Ngo's Catalogue of Philippines Republic Stamps & Postal Stationeries)