In many cases it is convenient to view the MCS function as defining a sub-left power rail whose connection to the main power rail is dependent upon some relay logic. The MCS function is entered without any reference, to create the control beginning point.
Logic is built using normal functions within the control area.
Note the duplication of contact 052, which adds only one memory word. You do not need to count or limit the quantity of relay contacts used in PCs. To end the master control, the MCR function is entered returning control to the next power rail to the left and conventional logic can now be built.