Mapping the human body is critical to improving our understanding by setting definitive reference points for organs, tissues, and cells of diverse types. In proteomics, a complete understanding of proteoform diversity requires measurements that systematically capture proteinlevel complexity. In projects like the Human Biomolecular Atlas Program (HuBMAP) and Human Cell Atlas, the resolution of mapping can handle single cells in tissues, with several highly multiplexed methods enabled by antibody-based affinity reagents: CODEX, Immuno-SABER, CyTOF, and MIBI, among others. These methods measure the expression of particular epitopes on proteins, though they still fail to capture the full complexity of the proteoforms present.