The union set of chromatin loops annotated for immortalized fibroblast cells (HFFc6) identified through the integration of multiple 3D genome mapping platforms, including Hi-C, Micro-C, CTCF ChIA-PET, RNAPII ChIA-PET, and H3K4me3 PLAC-Seq. Loops were identified using a hybrid loop-calling framework combining Peakachu with platform-specific algorithms, as detailed in the 4D Nucleome Consortium marker paper.