I haven't used Nyquist for decades, but why not post a detailed example and why you think the books are inconsistent? A lot of times explaining your problem in detail clarifies a block. Be carefull and pretend I know little. That makes for a better explanation, and is close to the truth. If you ask questions that I don't know perhaps Tim will explain; his book is eminently readable. I would suggest the example that you think is inconsistent and working against the description at:
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RayR