Pioneer HPM-100 Tweeter and Suptw. Level Control ?

Hi Community. Bought a great used pair of HPM-100s. No user's manual. I don't understand how to use the level control for the tweeter and supertweeter on the front of the speakers. Any experience with this anyone? The conotrol has a +2 and a -3 range, and then below the -2, on the same turning knob panel, are three dots, to which the knob will turn to. Does turning to one of the three dots cutoff the supertweeter and only allow the tweeter to work, or vice versa. . .or something else completely? Any experience. . .or additional thoughts about this speaker. . .would be very helpful. Thank you.
From the manual:

Level Controls

Individual controls are provided for the MID and HIGH frequency ranges, and when set at "0" a suggested output characteristic is obtained. Turning either control clockwise increases the output from that speaker, while turning fully counterclockwise reduces the output signal to zero.
My friend sold Pioneer speakers back in the 70's . His take on the HPM-100's sound best off the floor,sitting on a speaker stand... Grills off. Last, have the level controls cleaned with contact cleaner spray. Speakers of this age will need this tuneup. Happy listening.