In order to explore this notion, we analyzed the structures of the Enamine library dataset with the NPFC package and merged the PNP status information and the fragment combination information to the original full dataset. The resulting classification revealed that the Enamine library contains 32% PNPs (1.1 million in total and after deduplication by InChIKey), which is remarkably similar to the result obtained for the ChEMBL dataset. 270,000 NPLs and 4000 NPs were also identified. All other compounds were denoted y a " on-" status (fig. ).