QML is the representation of Q data in the standard XML format (an industry-standard format for hierarchical data). The format is described here in the QStudio documentation
                                                            
                                                     
                        
                                                
                        
                        
                            (Questionnaire Markup Language) — QML is the internal representation of a Perseus SurveySolutions questionnaire, and is used to generate a web form, an e-mail survey, a database and an AutoPresent presentation from a questionnaire.
                                                            
                                                     
                        
                                                
                        
                        
                            QML (Questions Markup Language) is an XML-based language for describing learning assessment items (questions). It was originally developed so that Connexions courses could present interactive questions to the students.