The USPS allowed considerable experimentation starting in the 1990's. This resulted in a rich CVP (computer vended postage) area in the US even though we missed the "Frama" development in other parts of the world.  Recently we developed the diagram below to get a handle on the many variations based on our understanding of the US DMM604.  We divided postage meters into three classes: Traditional Postage Meters, PC Postage (CVP) and Vending Postage.  Some of the PC Postage and Vending Postage types are similar to Postage Stamps in that they are undated and can be used at some time in the future.  Thus, the Postage Stamp circle is shown to overlap some of the items. This diagram is still being discussed (and can be somewhat controversial) and we expect change it. If you have information please join the MSS Discussion Group. 

We hope to provide similar diagrams for postage meters from other parts of the world with the assistance of collectors.

Updated 25 July, 2006