Dan Bloomquist wrote in news:xYhKh.5014$ya1.2122
@news02.roc.ny:

But your underlying principle is that the source steps and doesn't
change. So any general case where the source is at some different level
is now not covered.

It semantics Dan, the excitation is part of the scenario or example, it is
not a principle of circuits or transmisssion lines.

Owen