Sorry for the vagary. Scoring the mold is done by placing a casting with a perfect lip slot back in the mold and using a razor to delineate the lips' boundries on the mold's cavity. The castings should pick up the finest of lines. Pm me if you have any questions.
In any event, you'll have a true and consistent point of reference to use when cutting lip slots.
Everyone of these candy molds, and the many more that followed, has a Teeny, weeny, tiny imperfection from the master model, the orange one, that my old eyes missed. The buyer gave it a pass, as I had to point it out to him!
The point is that you can strategically place a reference point in your mold to use as a cutting marker. A hairline will suffice.