The old ZCL (Zone Control Last State) instruction is a "freeze" relay. You use it in pairs, similar to the MCR. From the rung below the first ZCL to the next ZCL (the ZCL "zone"), when the ZCL goes false or is de-energized by the trigger input(s), all outputs between the ZCL instructions are left in their last state (not changed from either on or off) even though their rung inputs may change while the ZCL trigger is on.
To simulate it in a SLC 500 program, one way is to set up a subroutine that includes all the rungs in the ZCL zone. Then use the old ZCL trigger input(s) to call the new subroutine. If the subroutine is not called, any outputs inside the subroutine are left in the last state before the subroutine call.
The first example is probably really the beginning of a new MCR group after a ZCL zone. The ZCL must have a corresponding ZCL end instruction, sooner or later. MCRs should NOT be overlapped with a ZCL. Overlapping MCRs and ZCLs result in unpredictable operation.
The difference between the ZCL and the MCR is that when false the ZCL freezes all the outputs in the zone, where the MCR when false turns off all outputs.