Extended Data Types in the Database [AX 2012]

Extended data types (EDTs) are user-defined types. EDTs are based on the primitive data types boolean, integer, real, string, and date, and the composite type container. You can also base an EDT on another EDT. EDTs can be used to define fields in tables as well as to define variables in X++ code.

This feature is not implemented as an X++ language construct. Extended data types are defined in the Application Object Tree (AOT) under the Data Dictionary > Extended Data Types node.

Caution
Starting in Microsoft Dynamics AX 2012, you can no longer define relations under an EDT element in the AOT. If your system has any EDT relations, you should migrate those relations to the appropriate table elements. For more information, see EDT Relation Migration Tool.