If you are planning to upgrade to the latest version of Dynamics AX (Dynamics AX 2012 R3 CU9) from one of the previous versions, take a look at the following table, which illustrates the upgrade options depending on the source Dynamics AX application version:
The source to target model is an upgrade option available for upgrading to Dynamics AX 2012 from the previous major versions (From AX 4.0 or AX 2009). In this model, the final data upgrade activity will move the entire database (all data, transactions, and companies) into Microsoft Dynamics AX 2012 R3. In order to minimize the downtime window of the upgrade, Dynamics AX 2012 provides the ability to preprocess the data in the source system. The following diagram shows the source to target upgrade model: