2016 Cougar 303rl 5th back flush

[etu]

I have a 2016 Cougar and have a question about the back flush option. My owners manual doesn’t cover it.
Below is a pic of the connection station.
Im assuming the top water hose connection is the tank flush inlet. But I’m not sure what is the “fullway termination valve” mentioned on the sticker next to that inlet. Would that be the black tank drain valve? 

[Kirk W]

As I look at your picture, the very top where the two knobs are with a fitting in between them is the outside shower connection, missing the hose and wand.

If you are asking about the caution sticker, it isn't clear enough to be legible so you need to take a close up and post it or tell us what it says. Does the cap just to the left of the caution sticker remove to display a hose connection, and if so is it male or female? I am guessing that it is female and is for the black tank flushing nozzle. 

Edited September 30, 2023 by Kirk W

[etu]

Sorry Kirk. Yes I understand all about the outside shower connections.
It’s the tank flush connector (female water hose) just below the shower fittings that I had a question. 
The sticker next to that water hose inlet says Do not use the tank flush valve unless the fullway termination valve is open…. I didn’t know what a fullway termination valve was.

I’ve since learned from other forums that “a fullway termination valve “ is a fancy term for black water tank drain valve. 
Thanks. 

[Kirk W]

11 hours ago, etu said:

I’ve since learned from other forums that “a fullway termination valve “ is a fancy term for black water tank drain valve. 

OK. I have never figured out why that name comes up, unless it might be from UK or AU or possibly Canada? I guess that I missed the meaning of your question. Having had and used a black tank flush system, the only things that I can think of that might warrant that warning would prevention of overfilling the black tank or perhaps the fully open part is to avoid solids hanging up on a partially open gate valve. The one that we had did have a caution to always use with the drain valve open, but I used to close the valve for about 5 minutes just before finishing the flush in order to get the rush of water to carry out whatever might remain in the tank. I did stand by the dump valve all of the time it was flushing just to be sure that I never filled the tank completely.