In Leon airport categories can be defined manually including a possibility to change the category as per each aircraft.
If you hover the mouse over the airport code, Leon will show a pop-up window with the information about the category, sunrise & sunset times and opening hours.
Click on the tab Brief to mark if the airport briefing is required (mark the checkbox 'Airport briefing required' or 'Training required or both). You can also upload a pdf file.
If in Airport Directory section you only tick a checkbox Airport briefing required for a particular airport (without a file uploaded), then the airport code in the flights list is marked with a black frame: