This board pictured is from a MightyFrame S/320, best we can tell. (Model CG-5140)
Without any MightyFrame hardware manuals as of yet, we can only guess what these jumpers are for. We are currently asking around. See the discussions at:
W2 & W3
W3 seems to be correlated with the MC68881 Math Co-Processor. It must be IN for the MC68881 to be recognized, and/or it must be OUT in if the MC68881 is not present. If both the chip and the jumper are not either both in or both out, the booting process hangs at various places.
Even though it's not marked on the board or the chassis, the center position of this Reset/Lock switch is what I would call "Run Mode". Without this jumper installed, the Lock position seems to do the same as reset, except that the switch locks in position, holding the board in reset mode.
More specifics can be added here.