The remaining two major sections of the PubChem PFAS Tree are compiled in a semi-automated manner using scripts in R and are integrated into construction of the entire PubChem PFAS Tree via mapping files. All code, mapping files and associated supporting files are on the Environmental Cheminformatics (ECI) GitLab pages . These sections and code build likewise on publicly available PubChem functionality, some of which was custom designed to enable the work described here, including adding new classification browser functionality to PUG REST. The final integration of this content into the PubChem PFAS Tree is programmed and run in PERL, as part of the routine described in the previous section .