Hello Carl,
Oh yes that's right, i must have missed seeing that part of the post. It says "negative polarity" so i would assume it's negative but not inverted ('negative' means multiplied by -1 whereas 'inverted' means simply inverted).
So lets see, a 10v amplitude pulse, inverted, is still a 10v pulse, unless they mean "negative polarity" to mean actually negative voltage, in which case his drawing would be correct. Usually if they mean 'inverted polarity' they say 'inverted', not negative, as 'negative' usually refers to a minus signal voltage, but we wont know for sure till he returns and clarifies.
So if the pulse was inverted and shifted by the offset we get one wave, but if the pulse was multiplied by -1 and shifted we get another, different wave (as his drawing).