King KA134 Intercom Question

I have a King KA134 intercom with a 44 pin connector.
The top row of pins are 1-22 and the bottom row are A-Z(22 positions?).
And there lies the problem. I'm not the smartest tool in the box, but I believe there are 26 letters in the alphabet. Does anyone know what alphabet characters are omitted from the A-Z (26) row?? Is there any chance someone may have the installation manual? Thanks

Should be marked on the pin connector BUT you may need magnification to see the markings.

Your probably right. I've gone through the Pin# description list I found online and it appears "Q,O,I & G" are omitted. The connector is still in the panel. Trying to avoid removing it to find out. Thanks