Some of you may recall that the post office used to issue a
new rate stamp when they were increasing the first class rate. But they had to wait for Congress to approve the rate so they didn't know what the new rate would be. Thus they prepared a stamp that did not have a cents listed. The first of these was simply called the A rate. They issued these several times with rate increases, B-rate, C-rate... the last one shown below was the H- rate issued in 1998.
In 2000 they issued the first "First class rate" stamp that had a fixed value Eventually they went with forever stamps beginning in 2007.
They had to decide on the change in 2000 because they did not want to issue an I-rate stamp.
True. Supposedly