Line Factory Algorithm

Yes, the documentation is very short. Here's a slightly longer version.

The algorithm first divides a phrase into spans ('Units' tab), each of which is assigned a segment type according to probabilities and learned patterns. Then it fills those spans with figure symbols using the Step parameter it generated for the phrase. Any symbols where the generated Pause parameter takes effect are left blank.

Each segment moves up/down according to the segment type (e.g. arpeggio) or whatever numbers you provide on the Segments tab.