ALT Today, we introduce a nomenclature that can express discrete PTMs, proteoforms, nucleoforms, or situations where defined PTMs exist in an uncertain context. Though specifically designed for the chromatin field, adaptions of the framework could be used to describe—and thus dissect—how proteoforms are configured in functionally distinct complexes across biology. Thank you to the many co-authors for your input and support. https://authors.elsevier.com/c/1lt5I3vVUPVb4c