I'm looking at the schematic of my BP Series I Boss 5, I see the terms IMF and IMR, I am assuming this has to do with the 3 phase electric motor? What does IMF and IMR stand for? Inductance Motor Forward and Inductance Motor Reverse?

Most probably 1MF & 1MR.
This is a common assignment to Contactor 1 Motor Forward and Contactor 1 motor reverse, and is applied to a dual reversing contactor for probably the spindle motor in this case.
In general they are interlocked both electrically and mechanically.
Al.

Thanks for the reply Al, I thought it had something to do with forward/reverse. When reversing are the leads L1 and L3 switched? Thanks, Ron