Let $G$ be a graph with vertex set $V=V(G)$ and edge set $E=E(G)$ and let $e=\vert E(G) \vert$ and $v=\vert V(G) \vert$. A one-to-one map $\lambda$ from $V\cup E$ onto the integers $\{ 1,2, ..., v+e \}$ is called {\it ...