In the 98 fsm, it seems that fogs are not restricted to low beam only, but it does seem the fog light switch also turns on the tail lights. I had a euro spec Mercedes 280TE gas wagon that had one fog tail light and one reverse light, fog light came on with the front fogs, and those fogs only worked in low beam. I had the euro spec headlights, though, reinstalled after the grey market inspection, and you didn't need any additional high beam illumination with those big old H4 bulbs...

Not responsible for advice not taken...