Yes, that is one of the feet of the machine, which has 4 bolt holes to attach to a table or qcw.
Screws are included with the machine to use in these holes to attach to a table top.
If you purchased the QCW, bolts are included with the QCW to attach the machine to the QCW.
Well, technically, no, that is not a hold down bolt. That is the foot the bolts or screws go into. I believe you need to provide your own bolts or screws if you don’t have a QCW (though I has been many years since I assembled a new one).
-Tom
is there a recommended size, length and diameter, for these screws? I am going to use shoulder bolts on my next table so they will absolutely not more after squaring the machine.
Not sure of the diameter as it has been a few years since I assembled my machine, but the length would depend on what you are bolting it to. mine run through the top of my homemade table with lock nuts on the bottom so they are pretty long.
Standard drywall screw works – I think that’s #8. Even then, plenty of space for larger - probably up to #12. @OnefinityCNC would know for sure.