
Vector control is only possible if you have 32 or 64 parts active. Setup is per MIDI channel, so you can have totally different vector behaviour on say channel 1 and channel 5.

In vector mode parts will still play together but the vector controls can change their volume, pan, etc. in pairs, controlled by user defined CCs set up with NRPNs

You must set the X axis CC before Y, but if you don't set Y at all you can run just a single axis. If you only have 32 parts active Y settings are ignored.

e.g.
Parts 1 and 17 can be set as x1 & x2 (volume only) while parts 33 and 49 can be y1 & y2 (pan only)

Independently of this Parts 2 & 18 could use filter and pan from another CC

Setting up is currently done as follows.

In the required channel send:
NRPN MSB (99)  set to 64, LSB (98)  set to 1  [8129]

Data MSB (6)      LSB (38)
      0         X sweep CC
      1         Y sweep CC
      2         enable X features
      3         enable Y features

Data LSB features values

Features:
        1 = fixed as Volume
        2 = default is Pan
        4 = default is Filter Cutoff (Brightness)
        8 = default is Mod Wheel
    
0x12 = 18 = Reversed Pan
0x24 = 36 = Reversed Filter Cutoff
0x48 = 72 = Reversed Mod Wheel

Setting the sweep CC for X enables vector control. It also sets, but doesn't enable the default X features.

Setting the sweep CC for Y sets, but doesn't enable the default Y features.

If you don't enable any features not a lot will happen!

The feature numbers are chosen so they can be combined. So, 5 would be Volume + Brightness and 19 would be Volume + Reversed Pan


Optional settings
   MSB          LSB
    4       x1 instrument ID
    5       x2 instrument ID
    6       y1 instrument ID
    7       y2 instrument ID
    
IDs are instruments in the current bank.

    8       new CC for X feature 2
    9       new CC for X feature 4
   10       new CC for X feature 8

   11       new CC for Y feature 2
   12       new CC for Y feature 4
   13       new CC for Y feature 8
              
Any data MSB value outside the above list disables vector control.

Sweep CCs and feature CCs are sanity checked.


An Example:

From channel 1, send the following CCs

CC      Value
99       64
98        1
 6        0
38       14
98        1 *
 6        1
38       15
98        1 *
 6        2
38        1
98        1 *
 6        3
38        2

This will set up CC14 as the X axis incoming controller and CC15 as Y, with X set to volume control and Y set to pan control.

You can either go on with the NRPNs to set the instruments (this will load and
enable instruments from the current bank) or enable and load them by hand.
For channel 1 this would be part 1 and 17 for X and part 33 and 49 for Y

The (*) CCs ensure that the data bytes are reset each time. This is not really necessary for the earlier commands, but should be done if you set the instruments with NRPNs as well, otherwise you will try to set them twice! 
