Adding Append Structures
Proceed as follows to create an append structure for an existing table:
A list of all the append structures which have already been created for the table appears. Choose New append. A dialog box appears in which you must choose a name for the append structure. The name must be in the customer namespace, that is it must begin with Y or Z.
You go to the field maintenance routine of the append structure.

Choose the field names in an append structure from the customer namespace for fields in order to avoid conflicts with fields inserted in the table by SAP. Customer fields should begin with YY or ZZ.
The table will also be activated when the append structure is activated. The fields of the append structure are appended to the table on the database.