There are several comprehensive systems for coding countries such as ISO, TLD, M49. I am looking for a system that is explicit about the time period that the code refers to.
My application is a research database for time series modelling on a global scale. For example I need to put one data point in for Germany in 1989 and one for Germany in 1990. If i use the ISO standard codes DE refers to all of Germany after 1990, but only west Germany before 1990.
Does anyone know of a system that not only updates for political changes, but includes a record of the previous iterations?
Update: the UN statistical division M49 three number code has independent codes for political entities before and after major changes. I'm still looking for something with clear ties to geography.