PO-Class and Data Flow in Classes 

PO class is persistent object and Base class for actual implementation. It is in VAdvantage.Model namespace. PO class is the main class, interacts with database for insertion, updation and deletion of the records. PO class is used to set Vienna default value for 7 mandatory fields for each table. All X classes inherits PO class.  

Vienna M Class contains business logic, each M Class inherit the corresponding X Class for getter & setter methods and all X Classes inherits PO Class. X Class will communicate with PO Class for saving the data in the database. PO class directly interacts with database to save and retrieve data.