The "PFAS and fluorinated compound collections" contains five major sources of suspect lists (see top right inset of Figure ), including NORMAN-SLE , CompTox 11 , OntoChem , PubChem and NIST . The CompTox chemical list content is retrieved programmatically from the PubChem EPA DSSTox Classification Browser () and curated manually to retain only PFAS lists, which are included in the mapping file to retrieve the respective CIDs in each list via their classification hierarchy node identifier (HNID). The files containing the CIDs for the remaining four sources are hosted on the ECI GitLab pages; the URLs for each file are contained within the mapping file used for retrieval during the PubChem PFAS Tree construction. The NORMAN-SLE subsection contains all PFAS lists within the NORMAN-SLE (currently 12); one CID list was manually adjusted to remove non-PFAS entries such as counterions. The OntoChem CID lists are broken down by the three PFAS definitions and two data sources to form 6 categories. The NIST PFAS Suspect List was downloaded and deposited to PubChem (resulting in 1,232 new CIDs, i.e., new compound record entries in PubChem) and updated once all new CIDs were registered. Finally, the PubChem content was compiled by identifying several fluorinated compound sections in other classification browsers, including the MeSH, Cameo and ChEBI browsers. Since the NIDs were not always stable (especially for ChEBI), these were also added by providing fixed files via the GitLab pages. These lists and mapping files are updated as necessary under full version control in GitLab ; all updates appear with the next PubChem PFAS Tree update.