For state record...

State record is used for providing the variables, database fields to different sections of the application engine. Scope of the state record is limited to the application engine program. AE can have multiple state records, but can have only one as a default state record.

It can be physical or derived work record. Physical record can be used when you have a restart logic and when you have disables the restart logic derived and work record can be used.

The naming convention is, it must end with _AET identifier and process instance should be the one and the only key for the state record, so that application will identify the record as a state record.