Data property is a property which value is stored in the database and may change through the execution of the corresponding action. Each parameter and the value of a data property must belong to a certain specified class. If a parameter does not belong to the specified class or is NULL, then the property value will return NULL.
Local data properties
Data properties can be local. Such properties retain their values only within the session, i.e. they are not saved to the database, which means when applying changes these values are reset to NULL by default.
To declare a primary property, use the DATA operator.
quantity = DATA LOCAL INTEGER (Item);
isDayOff = DATA BOOLEAN (Country, DATE);