Can VELUX skylights be installed sideways?

The VELUX Fixed Curb Mount Skylight (FCM) and Fixed Pan-Flashed Skylight (QPF) are the only two skylights that can be installed sideways. All VELUX deck-mounted skylights, Skylight Systems skylights, and flashing systems have a "true top".  None of them can be installed sideways. If any skylights other than the FCM and QPF are installed sideways, the warranty on them will be voided.