You're looking for structures and style in the authors writing.
On the whole the non conscious mind is better at solving patterns than the conscious mind. So while you may not exactly know what "the pattern" is consciously the non conscious does pick it up. So during preview/postview you are more interested in the nature of the author language, humour or lack there of for example. The layout of the book. How it is set up. What usually follows the bold or subheads. Is the author in the habit of emphasising words within the text.
While you're consciously getting a general look where everything is in the book and what order it is in the non conscious mind has probably noted whether the author the what or why firs in each paragraph.
For you're preview, review questions turn back to your purpose for reading and let the nonconscious mind handle the aspects of "patterns" within the book.
If you're having trouble with answering or forming questions its more important to check your purpose than the book.
There is no point consulting the map in a lot of detail if you don't know where you want to go or guess at what you would like to see along the way.
Alex
