Since SAP NetWeaver 7.5 SP00, you can create and work with data elements in ABAP Development Tools (ADT) using the form-based editor. You create and edit data elements to define an elementary data type or a reference type.
You can only create and edit data elements in a form-based editor if your IDE is connected with SAP NetWeaver 7.5 SP00.
For more information, see Data Elements in the ABAP Keyword Documentation