Reply by FirehouseWoodworking

I would presume that they may actually be a trammel point of sorts.

The bar would function independent of the fence. One would slide the bar out of the fence and install the bar onto the router. Set the distance from the pointed pin to the router bit and viola’. You are routing circles!

Least ways, that’s my story and I’m sticking to it.

Cheers!

-- Dave; Lansing, Kansas