SBO terms found on SBML Reactions do not all map to the SBO terms that are supported in BioPAX. The discussion that came out of this problem for the GSoC 2016 program was to suggest to have BioPAX annotate the SBO terms that are unable to map from SBML to BioPAX. Currently, the SBML2BioPAX conversion will drop these SBO terms in SBML Reactions that do not directly map over to BioPAX.