Standard cone is a cone of the standard lattice defined as follows.
That is, for a subset A of standard lattice L3, Cone A is a set of points (l, m, n) in R3 …
Cone A specifies “peaks and valleys” of the standard lattice …
For example, as shown below, the “peaks and valleys” of the previous example is Cone { x1lx2mx3n, ... }.
Since standard cones specify the “gradient” of slant triangles, we could call them “tangent” cone.