earlier study [@EQU] and convertibility of their solutions is proved. For a given index coding instance, we modify a given side information graph by adding receivers, messages, and edges or by deleting some edges in order to derive the corresponding network coding instance in a similar manner. We also show the convertibility of their solutions if a pair of encoding functions of an original link and the duplicated link are functionally related in the network code. Our models of the corresponding instances not only offer convertibility of the coding solutions but also ensure that a given network (index) coding instance is identical to the re-converted network (index) coding instance from the corresponding index (network) coding instance. Moreover, the equivalent index coding instance of a given network coding instance does not contain the receiver $\hat{t}_{\rm all}$, which was given in the earlier studies [@EQU], [@FEQU]. In [@SEQU], it was noted that an equivalence between secure network and index coding can be achieved without $\hat{t}_{\rm all}$. Similarly, we prove in detail that the receiver $\hat{t}_{\rm all}$ of the corresponding index coding instance is redundant in general. Since an NCLE and an ICSIE are equivalent, we derive several properties of an NCLE from 