has participant ceasing to exist has specified reactant A relation between a planned reaction step and a molecular entity participating in that process that is not created during the process. The destruction of the molecular entity during the process is explicitly specified in the plan specification which the process realizes the concretization of. RXNO RXNO:0000424 The difference between this and OBI's has_specified_input is that it is necessary that the reactant ceases to exist during the process. molecular entity planned reaction step