The Consortium for Top-Down Proteomics (CTDP) defined the initial 1.0 ProForma notation to encode exact proteoforms with all applicable PTMs on a specific sequence. When the PSI needed a mechanism to encode in a compact way exact peptidoforms (peptide sequences with a specific set of mass modifications), ProForma provided a useful piece of prior work on which to build. In collaboration with the CTDP, the PSI has recently developed the ProForma 2.0 standard, which provides a substantially expanded set of mechanisms to encode a wide variety of modified proteins and peptides (proteoforms and peptidoforms) in a manner that meets the needs of both the CTDP as well as the bottom-up proteomics workflows. The ProForma 2.0 formatting is both easily human readable as well as software parsable. The ProForma 2.0 standard is used in conjunction with other completed and in-development PSI standards as described below.