How do emergency roof hatches (Dachnotausstiege / Dachluken) operate on an Austrian touring coach during an emergency evacuation?

1. They can only be opened using an electric key kept at company headquarters
2. They feature an emergency release lever or push-out mechanism that completely ejects or swings the hatch panel open, creating a large, clear overhead exit portal
3. They are purely decorative ventilation louvers with no emergency opening capability
4. They automatically weld shut when the bus engine stops