We were trying to create an extension for LAYMOD01 IDoc. But we were getting an error. We found that we were unable to extend the IDoc because there was an entry in the field gen. in the table EDBAS for message type LAYMOD. When i deleted that entry in the table, the Idoc could be extended and our requirements solved easily. I just wanted know if there can be an issue with extending the Idoc this way.
I looked at our system in table EDBAS and found that nearly 50% of the entries do not have the field GENERATED checked. I think if the IDOC is manually created, this field will be blank. This may be the reason for your message during extension. However, the functionality of IDOC type does not depend on this field. But during Enhancement Pack application or upgrade time, you may have to update this field again.