Persistent codes are codes defined for OOM classes and attributes that are used during OOM to CDM generation. They also facilitate round-trip engineering by allowing you to recover object codes from the conceptual data model.
All persistent classes are generated as entities. If you set the class generation mode (in the Persistent group box in the Detail tab of the class property sheet) to "Migrate columns", the Generated check box in the generated entity property sheet is cleared by default.
You can also define persistent data types for class attributes and domains. For data type persistence management, you have to take into account the following parameters:
The data type is simple, based on standard OOM data types. If the data type is persistent, generation keeps persistent data type in the target model. Otherwise data type is converted to standard data type in the target model
The data type is complex, based on a classifier. If the data type is persistent, you can define different generation options according to what you want to have in the target model and to the attribute multiplicity