In 1937, after much debate, a new definitive series was issued using Roosevelt's ideas.
The next definitive series did not come out until 1960, the 15 values depicting various native birds.
Six definitive series on India's heritage and progress in a number of fields have been issued.
This was followed in September by a definitive series using the same design as before, with the monarch's profile updated once again.
Another definitive series appeared in 1964, also with nine values.
The next definitive series was a set of scenic views issued in 1934.
The first definitive series of the republic, in 1960, depicted masks from various tribes.
In 2001, a second definitive series completed Marianne: a black and white map of the island.
Over the last 60 years, 17 definitive or regular series have been issued.
Finally, it is common for the stamps of a definitive series to be issued one or a few at a time, as postal rates change.
