My humble opinion:

L1 = W+T1+P1+D1 (OPE)
L2 = WNC+T2+D2 (OPE)
L3 = W+P1 (SUS)
L4 = WNC (SUS)
L5 = L1-L3 (EXP)
L6 = L2-L4 (EXP)
L7 = L5-L6 (EXP)

and the reason is that you always have a sort of "check point" which is installation temperature.

I hope that I've made myself clear..

In order to go from W+P to WNC, first you have to shut down and empty the line. If, for example, you have a system that will always operate at instalation temperature W+P-WNC will never be secondary.

If not, there are a lot of lines full of liquid that have also the "steam out" condition. I think that nobody made a check W+P-WNC.


Best regards,