India has been divided into 22 postal circles.
Each circle is headed by a Chief Postmaster General each circle is further divided into Regions comprising field units, called Divisions, headed by a Postmaster General.
During the above period all the Circles in India adopted number cancellation with a letter assigned to each circle and giving the number of the post offices and the special post offices either with a circle preceding the square number cancellation or by the number cancellation itself.
The four varieties of these cancellations are as below. In the year 1879 the rectangular shaped cancellation consisting of heavy parallel bars framing the letter denoting the headquaters of the circle came in use & some time later the circular shaped cancellation with parallel bars framing the letter denoting the headquaters of the circle also was in use The distinguishing letter assigned to each Circle for the first letter of the headquaters office is as follows: