What is on the drawing
A line of numbers, in millimetres, marked on the patch that sits under your eye during the set. Typically nine at the inner corner rising to twelve somewhere past the middle and back down to ten or eleven at the outer edge, though every one of those changes with the eye.
It also carries the curl, which can vary across the line, and the diameter your natural lashes will actually carry. And then the artist works to it, lash by lash, for two hours.
It is the whole set. A perfectly executed set on a bad map looks worse than a merely competent set on a good one, and it is the reason a first appointment here starts with ten minutes of drawing and five minutes of talking rather than with a tray of lashes.
Why past centre
Length concentrated at the outer corner pulls the visual weight of the eye downward and outward. It reads as tired, or at best as heavy, and it is the single most common error in lash mapping because it feels like it should be flattering.
Length just outside the centre of the eye, roughly above the outer edge of the iris, does the opposite: it opens the eye vertically and makes it look rounder and more awake. Which is what almost everybody is actually asking for when they bring in a photograph.
Except when it is not
A round eye often wants the peak further out to lengthen it. A hooded eye wants shorter and straighter through the centre where the lid sits closest, or the extensions simply disappear under the fold. A downturned eye wants the peak clearly inside centre to lift it, and a very close-set eye wants nothing much at the inner corner at all.
Reading that in about four seconds of looking at a face is most of what experience buys, and it is why “which set do you want” is a much worse opening question than “what do you want your eyes to look like.”