aDAve, I'm not sure what color silver you want the platter to be, but since there is a section entitled "How a ladder is scanned" I don't understand your failure to find "not a sausage" in the link
http://www.plcs.net/contents.shtml
Note that a technical education is as much about thought processes and problem solving techniques as it is about information. You have to learn to draw conclusions and make logical deductions from information not directly answering the problems you are trying to solve. It is rare to find exactly the answer to exactly the question you have phrased in exactly the same manner as the asking!
Finally, is the text for the course totally silent on all of the subjects in your initial inquiry?
(Edit - Wow - many of us are giving the same answer almost simultaneously. Is it a matter of great minds thinking alike, or are we all travelling in the same rut?)