Lost to history is the fact that XFree86 version 3 provided a different binary for some families of graphics card. If you owned an S3 911 (a very common "Windows accelerator" at that time) you needed XF86_S3 but if you owned one of S3's execrable ViRGE 3D cards you needed XF86_S3V. Having a single server that contained or could load every driver did not come until version 4.