| Value | Category | 
                                    
                    
                        | 0 | No School | 
                                    
                    
                        | 1 | Sub. A | 
                                    
                    
                        | 2 | Sub. B | 
                                    
                    
                        | 3 | Std. 1 | 
                                    
                    
                        | 4 | Std. 2 | 
                                    
                    
                        | 5 | Std. 3 | 
                                    
                    
                        | 6 | Std. 4 | 
                                    
                    
                        | 7 | Std. 5 | 
                                    
                    
                        | 8 | Std. 6 | 
                                    
                    
                        | 9 | Std. 7 | 
                                    
                    
                        | 10 | Std. 8 | 
                                    
                    
                        | 11 | Std. 9 | 
                                    
                    
                        | 12 | Std. 10 | 
                                    
                    
                        | 13 | Other | 
                            
            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.