What accessibility requirements must be observed for Wheelchair Users (Rollstuhlfahrer) on public transport buses under the Swiss Disability Discrimination Act (BehiG, SR 151.3)?

1. Use the ramp but position every wheelchair in the aisle because it is closest to an exit
2. Require every wheelchair user to transfer to a standard seat, regardless of the approved accessible arrangement
3. Use the approved accessible boarding arrangement and designated wheelchair space for that vehicle, deploy ramps or lifts correctly, follow its securing/backrest instructions, and keep accessible controls and routes unobstructed
4. Apply one four-point tie-down method to every bus, even when the approved vehicle instructions specify a different arrangement