| Value | Category | 
                                    
                    
                        | 1 | 1. DMY given | 
                                    
                    
                        | 2 | 2. MY given, DK D | 
                                    
                    
                        | 3 | 3. DY given, DK M | 
                                    
                    
                        | 4 | 4. Y given, DK DM | 
                                    
                    
                        | 8 | 8. DK DMY | 
                                    
                    
                        | Sysmiss |  | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.