Replying to Help with describing a -2 mounting point on Scratch FS WRS to online store

I'm ordering my skis online in a few minutes and I need to describe to the store what -2 from true center means. (I've already searched)

I'm sure they understand how to find the exact middle of the ski and measure back 2cm for a mounting point, but I've heard too many stories of people getting their skis back and they are mounted incorrectly.

Can someone let me know how far forward of modern is -2cm, untracked.com is saying that the core center point is +7, but I don't know if that's +7 from standard or +7 of modern

Does Rossignol consider core and true center the same thing? (I read in a previous post that they do). I'm used to K2 using both terms as two distinct spots.

Thanks for the help