1948-49: O.B. overprints

The first official stamps of the Republic era were five definitives of 1947 overprinted O.B. (for Official Business) issued on different dates:

May 1, 1948 (4c and 10c)
May 28, 1948 (16c)
January 23, 1949 (50c)
July 4, 1949 (20c)

The overprinting was done by the Philippine Bureau of Printing for the 4c, 16c and 50c and both the Philippine Bureau of Printing and the American Bank Note Company for the 10c and 20c.

Quantities printed:
4c (14,998,500)
10c (9,499,500)
16c (999,898)
20c (4,500,000)
50c (400,000)

A total of 787,879 of the 16c was withdrawn on July 26, 1950.

There are two measurements of the O.B. for the 10c:
13mm Manila printing
12-1/2mm New York printing

There are two measurements of the O.B. for the 20c:
13-1/2mm Manila printing
13mm New York printing

Errors:
4c overprint inverted, overprint doubled

Shifted overprints:
4c leftward, rightward (the extreme is B.O. instead of O.B.)
10c leftward, rightward, downward
16c leftward
20c rightward

Varieties:
10c small period after O

[Data taken from various sources.]