Each line is a Tone’s output to an effects unit, and the circles with arrows are attenuators setting the send levels to the three effects processors.
Here Part 1’s Output Assign is set to EFX, which ignores the individual Tones’ send levels in the Patch. Part 1’s own send levels replace them for all active Tones in its Patch.
Diagram from the XP-80 Owner’s Manual, © 1996 Roland Corporation, reproduced for educational purposes. Credits & disclaimer.