Like PFOA, the LC-PFCAs section remains difficult to complete due to the sheer number of chemicals involved. This is primarily due to the wording choice in the definition for the "related chemicals". As for PFHxS, two definitions are being explored for LC-PFCAs, the Stockholm Convention nomination of C 9 -C 21 LC-PFCAs and the EU REACH definition of C 9 -C 14 LC-PFCAs . The CIDs contained within these sections currently fulfil the LC-PFCAs, branched isomers, salts and mixture requirements of the regulation, but have not been extended to the related substances which, even in the current incomplete state, covers an additional 18,275 entries (the "related substances" sub-section remains as work in progress as the functionality required to perform these queries efficiently and automatically is still being developed). The C 9 -C 14 LC-PFCAs section is constructed using the "PFAS breakdowns by chemistry" section of the PubChem PFAS Tree and contains 230 CIDs. The C 9 -C 21 LC-PFCAs section contains 745 CIDs, which includes the draft indicative listing (83 CIDs), compounds that transform to LC-PFCAs (3 CIDs), plus queries for C 9 -C 21 LC-PFCAs, their branched isomers, salts, and mixtures. In total 584 of these have some form of annotation content, including 129 with use, 34 with safety or toxicity, 47 with literature, 490 with patent information, and finally 38 CIDs created recently (from 2022 or 2023). Again, these categories help determine which of the C 9 -C 21 LC-PFCAs may be relevant for different use cases.