bonmur-
I honestly think that the wording is incorrect if you're sighting what you posted from a specific chapter in a book. Only in the sense that a Dandie Dinmont doesn't have a "roached" back, but rather a significant curvature of the spine. There really is a difference. Proper wording is much needed when it pertains to most things, dogs especially. If someone told me that a dog is big, I think large as in weight. But, many people I speak w/ will say "big" meaning "tall". If someone tells me that a dog is tall, well that's more descriptive and concise. I then know that the dog is...tall. Do you see what I'm saying? Nit picking, yes, but that's me!
And yes, one could say that a significant curvature of the spine is a recessive gene within the breed, however that's indicative of many traits seen within many breeds from their origins. This is why it's terribly important that we have a standard. A phenotype that we strive for. With one inherited genetic phenome that comes out of the wood works, often come many. And not all recessive genes are as benign as a curvature of the topline.