This is just one of over 75 professional audio mixers covered in The Mixer Output Guide, which describes direct outs, inserts, hidden mods and more. To see the rest, and for definitions, visit The Guide.
Direct Out:
TRS balanced, "impedance balanced" on mono inputs only, post EQ pre mute by factory default, internal jumper mod for pre EQ/pre insert. 0dBu.
Insert:
1/4" on mono inputs only, TS/RR, Pre-EQ. "Multi Function" channels are different, see manual.
Gain Control of Direct Output: