What is IBM system board removal? you have real information about it?

To remove an IBM system board from its case,simply remove the two or three screws holding it in place after you have  removed all the expansion boards from their slots and disconnected all the wires plugged into the system board then slide the board about one inch to the left freeing the nylon fasterners from their channel.you should then be able to remove the
board from the case by lifting its left edge above the rim of the case and countinuing to slide it to the left. planar boards in ps/2s do not require the left shift when they are removed because they are simply held in place by their  mounting screws once you are removed the screws holding the planar down,you should be able to lift it free.