Is there an established standard term for the concept described in the details?

Question

If $N$ is a finite set of points in the 2-D Euclidean space, then let ${\tt ch}(N)$ denote the convex hull of $N$, and let $$ \partial {\tt ch}(N) $$ denote the boundary of that convex hull. I need to operate with the subset of $N$ consisting of all those points $x \in N$ that lie on $\partial {\tt ch}(N)$. For my purposes, it will be convenient to call this subset something; e.g., the outer layer of $N$. (I will then define, recursively, the $k$-th outer layer of $N$.) But am I reinventing the terminological wheel? In other words, does there already exist a standard term for this?