In AX 2009, We all know that Table relations were defined only through EDTs and this was a problem if multiple relations were needed between tables, or if relations involved composite keys.
In Microsoft Dynamics AX 2012, relations can no longer be created under extended data type (EDT) nodes in the Application Object Tree (AOT). Relations that are defined under EDT nodes are still effective, but in a future release they will be obsolete and deleted.
The EDT relation migration tool helps you move relations from EDT nodes to table nodes. The EDT relation migration tool is found on the client menu, under Tools > Code upgrade > EDT relation migration tool.
For more information : click here.