Speeding Ticket Bleg

I received a speeding ticket today (corner of Route 50 and N. Edison, eastbound on 50, laser sped trap, for our Northern Va. readers). I happened to have glanced at my speedometer at the bottom of the relevant hill, and the officer claimed that he clocked me way above that speed at the top of the hill (and I wasn’t braking or stopping short at the bottom!).

Needless to say, I plan to challenge this ticket. Two blegs: First, under the charge description, it says “OPS 6 + 663.7.” What the heck does that mean? Second, is there any good basic manual out there for challenging laser tickets, especially with reference to Virginia law?