From your 1995 owner's manual (also available online at the Volvo website, if you've lost yours)

pg. 1:8 Instrument illumination, Fog lights, Daytime running lights

" B - Rear foglight (one side only)

The rear foglight (located in the driver's side tail light cluster) is considerably brighter than the normal tail lights and should be used only when the atmospheric conditions, such as fog, rain, snow, smoke or dust reduce the daytime or nighttime visibility of other vehicles to less than 500 ft (150 meters).
For the rear fog light to function, the low beam headlights must be switched on."

AND

pg. 1:3 Indicator and warning lights

"4 Low washer fluid level
If the lamp glows continuously when the engine is running, there is only about 1/2 - 1 US qt. remaining in the washer fluid reservoir.
5 Low fuel level
When the lamp glows, only about 1.8 US gals. (8 liters) of fuel remain.
6 Rear fog light
7 High beams
8 (Not in use)
9 Bulb failure warning sensor