The purpose of this crosscheck is to force the crosscheck process to fail. In other words, select this crosscheck if you want all records that match on a primary key to be queued for MCU.
For example, say you have identified a bunch of duplicate records, and you want to take advantage of the MCU interface to look at them. Unfortunately, MCU will not load a file that hasn't been previously grouped by PLP. To get around this, use the XXXXX crosscheck: setup some match rules that will group these records on the appropriate primary key, using only the XXXX crosscheck, and then pass these records through Self-PLP.
You will then be able to view the results in MCU.