in NRZ-L, is does positive represent 1’s or 0’s?
In your first example you wrote positive as 1 and negative as 0, but you inverted it later on.
Or can it be either way?

And in NRZ-I, how does the receiver know whether the first bit is 1 or 0?

Actually, now that I think about it, NRZ-I probably just ignores the first “bit” and starts reading from the second “bit” onwards. (so ignore my second question)

in NRZ-L, is does positive represent 1’s or 0’s?

In your first example you wrote positive as 1 and negative as 0, but you inverted it later on.

Or can it be either way?

And in NRZ-I, how does the receiver know whether the first bit is 1 or 0?

Actually, now that I think about it, NRZ-I probably just ignores the first “bit” and starts reading from the second “bit” onwards. (so ignore my second question)

For RZ, is it always necessary that 1 represent +ve voltage while 0 represents -ve voltage?