The following extended attributes are available:
| 
                             Extended Attribute  | 
                        
                             Description  | 
                    
|---|---|
| 
                             default-fetch-group  | 
                        
                             Specifies that the attribute is managed as a group with other attributes. Tag name: default-fetch-group  | 
                    
| 
                             embedded  | 
                        
                             Specifies that the attribute should be stored in the instance instead of its own instance. Tag name: embedded  | 
                    
| 
                             null-value  | 
                        
                             Specifies the null value treatment. The default value is none. Tag name: null-value  | 
                    
| 
                             persistence-modifier  | 
                        
                             Specifies the persistence modifier. Tag name: persistence-modifier  |