A PYXIS index uniquely identifies a cell and cell resolution in a hexagon tessellated icosahedral Discrete Global Grid System.
Because a Vertex Parent has only a centroid child, non-zero digits cannot be adjacent. (I.e., 0123 is not a PYXIS index.)
On the Icosahedron, PYXIS indices are prefixed with a letter (A through T) or number (1 through 12) identifying the root cell. A letter denotes a face tessellation (i.e. hexagon) and a number denotes a vertex tessellation (i.e. pentagon). Such indices look like A-040506 or 1-203.