Metasequencer Sequencer

I have spent hours trying to work out how to use Metaseq but I still don’t get it…
https://www.netpd.org/Metaseq

I can get the basic function of it - i.e. I can chop a 4 bar pattern up and play it in a different order - but i’m having trouble understanding the next level of sequencing, using one set as the clock for another set. i can’t make sense of the way the segments on the right panel are treated.

Can anyone help me to understand it a bit better?