Recto 2x12 jack plate question

I have a mesa recto 2x12 that I recently installed the road king plate so I can run the cab in stereo with my 2:50 power amp. I know that I could have just cut the jumpers on the original plate, but I want to be able to go back and forth from mono to stereo depending on which gear I use. I'm still not clear on one thing though. What is the "Paralled Out" jack used for? I might want to install this extra jack into a blank cab and want to know if I should leave the jack as it is. Thanks for any help.

Sean

The parallel out enables the ability to connect one cabinet to another so that they will be in parallel rather than in series.

Great, thanks. So if my boogie cabinet is 8ohm and I have another 8ohm cabinet, the parallel out daisy chained together will make the amp see a 4ohm total load.

Correct