[Elecraft] KX3 - KXPD3 Socket, Plug, and Schematic Questions

[Richard]

Hello,
   Why is source 3V3D connected to Pin 3 of the KXPD3?
   I have made (but not yet used) an interface cable to connect external 
paddles to the KXPD3 jack.  The  KXPD3 Schematic shows Pin 3 of the plug 
grounded inside the KXPD3.  However, Page 2 of 8 of the Control Panel 
schematics shows 3.3 Volts (3V3D) connected to pin 3 of the KX3 socket 
through R110.
   Testing by another ham found that connecting Pin 1 (grounded inside 
KX3) to his external key common and the Dit and Dah leads to pins 2 and 
4 worked fb.  The KXPD3 schematic shows Pin 1 not used.
   My KX3 socket pin measurements to chassis:  Pin 1: Grounded,  Pin 2:  
11k,  Pin 3:  2.1k,  Pin 4: 11k
   Is Pin 1 or Pin 3 the common contact terminal inside the KXPD3? Is 
Pin 3 grounded inside the KXPD3?  (I would ring it out, but I don't own 
one.)
   Do nDASHALT and nDOTALT go low (like the side key jack) or high to 
indicate contact closure?
   If the former, why is 3V3D connected to the KXPD3?
   Thanks for any assistance to help me understand.
    73, Richard, AI4SH