The Manually Check Pathway (MCP) list contains a very small number of pathways that are likely to be relevant to the users of the databases and are likely to be reported in published literature for many plant species. The current manual list contains four pathways: three pathways describe different C4 photosynthetic variants and one related to photosynthesis in seeds. Curators attempt to find references to determine whether any of the pathways on this list exist in a given species whenever they are predicted using the Pathologic program