I can't be bothered to read the whole thread again so it might have already been said.
However, over-thinking has been prevalent and along with the poor choice of words; namely bidirectional and unidirectional; it has led to confusion.
As far as I can tell the terms just mean that...
I am not sure I understand all this.
Leaving aside the fact that it is 'alternating current' so presumably going both ways everywhere anyway.
Through the RCD, the Line current and Neutral current (while alternating) go in different directions. If this were not the case the RCD would not and...
Don't you mean higher?
Yes, there are infinite possible values of every part.
Yes, I was going to write something along the lines of: given the choice of either SB or RCD I might (now) choose the SB.
Perhaps this will persuade @equitum that SB makes a difference - and what a difference; it alters just about everything.
I think I have calculated it all correctly but if anyone sees an error please let me know.
From the first of Flameport's links.
So - either another totally inappropriate name for an electrical item or possible an inaccurate translation from the original.