Only hydroquinone is listed as a developing agent. It's very uncommon to have only hydroquinone without something like metol or phenidone in a commercial print developer. So either this information was left out of the msds, or it's a fairly unique developer. My money is on the former, but that would put it in one of several developer families (most notably MQ and PQ) each of which has many variants. Conclusion: the msds does not allow for identification of a direct substitute.