The current implementation of SynRBL is limited to product-dominated or reactant-dominant reaction entries. Moreover, it does not cover certain types of carbon-unbalanced reactions, in particular cyclizations and other complex rearrangement reactions that are difficult for the MCS-based branch of the framework. The SynRBL software is designed, however, to facilitate future extensions of the rule sets as well as of the MCS strategies. SynRBL is not based on a machine learning approach.