Which lessons cannot be exported to STSWEB?

To see the list of non-exportable lessons, go to the display Timetable > Lesson > List, then click in the menu on Extract > Extract the non-exportable lessons to STSWEB: EDT displays only non-exportable lessons, indicated by the icon in the column STSWEB; a long click on the icon indicates why the lesson cannot be exported. If you do not see the column STSWEB, click on the button at the top right of the list to display it.