Event Handler Extension Table 
An additional table in which you can define your own fields that you can then use for search and report queries.
The extension table is found in the event handler header data. System parameters are mapped from the application system to the fields in the extension table. (See also: section.)
The user can use the fields in the extension table as additional options for search and report queries about event handlers. For more information about adding additional data from the extension table as selection criteria in the event handler list, see Defining Search Criteria .
Note
Fields in the extension table must not contain numeric domains. Only use character-type data types for the domains.
For more information, see the Implementation Guide (IMG) for SAP Event Management under