The identity code $C$ of a graph $G$ is the dominant set of $G$ such that any two distinct vertices of $G$ have distinct closed neighborhoods in $C$. These codes have been extensively studied for over 20 years. By proving the upper bound on $(n+\ell)/2$, we improve on all the best known upper bounds, including the one that has been used for over 20 years to identify code in trees. increase. where $n$ is the order. $\ell$ is the number of leaves (drooping vertices) in the graph. In addition to being an improvement in size, the new upper bound actually holds for bipartite graphs that do not have twins (pairs of vertices with the same closed or open neighborhood) of degree 2 or higher, thus improving generality. There is also. We also show that infinite class graphs have narrow bounds, and that there are several families of structurally distinct trees that achieve the bounds. We then use the bounds to derive a strict upper bound of $2n/3$ for a twinless bipartite graph of order $n$ and characterize the extremum example as the $2$ coronal graph of the bipartite graph . This is most likely because there are graphs without twins and trees with twins that require $n-1$ vertices in any of the identity codes. We also generalize the existing upper bound of $5n/7$ for graphs of order $n$ and generalize around at least 5 in the absence of leaves to the upper bound $\frac{5n+2\ell}{7}$ become Leaves are allowed. This is tight for $C_7$ and all stars in the $7$ cycle.



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