Er, not quite. <engage nitpick mode>
The wireless operator usually had the most control, via Control Unit No.2 (or 3, 6 and 16); the commander (in a multiple control unit installation) would have access to all sets + intercom, and most other users would be Intercom only.
The N/R switch is "Normal" and "Rebroadcast", which allows the receiver output of any set to be retransmitted using a particular other set. This can get quite complicated in things like Command tanks, with a 2 or 3-set installation and Control Units 16 and 17 (or 33), or the ACV/LCV setup with 2 sets and Control Units 4 & 6.
Rebroadcast facilities are on the Operator control unit (2, 3, 6 or 16), the Commander's unit will be a No. 1, 4, 17 or 33 and just allows the droplead to be switched to particular set outputs or intercom.
No.6 is the most complicated that I've encountered, for two WS19s in a command vehicle. (Though I believe there was also one (No. 39?) that allowed a WS38/31/88 AFV set to be added to the mix.)
No.6 settings:
Operator droplead switch positions: A1, IC, B, A2, R
In the "R" position, the 12-position switch comes into play. There are three "Listen" positions for monitoring, where the transmit switch is disabled:
1) "Listen All (A1, B, IC & A2)"
2) "Listen A1 & B"
3) "Listen A2 & B"
There are then three sets of switch positions, controlling the Rebroadcast function. The middle position is for the control operator - to announce the rebroadcast, then switch the traffic in appropriate directions when required (in the middle position transmit is controlled by the operator's microphone, in the other two (rebroadcast) positions the set is locked on transmit and the operator's microphone disconnected - headphone is still connected to the set being rebroadcast, of course, so the operator knows when to switch the rebroadcast direction).
4) B -> A1 (rebroadcast B set on A1)
5) B + A1 (receive & transmit on both - for setting up rebroadcast)
6) A1 -> B (rebroadcast A1 set on B)
7) A2 -> B (rebroadcast A2 set on B)
8) A2 + B (receive & transmit on both - for setting up rebroadcast)
9) B -> A2 (listen A2. R: rebroadcast B set on A2)
10) A2 -> A1 (rebroadcast A2 set on A1)
11) A1 + A2 (receive & transmit on both - for setting up rebroadcast)
12) A1 -> A2 (rebroadcast A1 set on A2)
I suspect using this facility took a lot of practice!
The red light (on the Operator control units) is "A set unattended" and is to warn you that no headset is switched to the "A" set position.
Control Unit No.16 just added the "C" set (WS38, 88, or 31 AFV) to a standard No.2 control unit, the No.17 was the commander's version (No.1 with AFV set), and No.33 is a command tank version of the No.17 with A1, IC, A2, 31/88AFV positions (the 'B' set had been discontinued at this point and its switch position repurposed).
Yes, it's complicated.
Chris.