Table heading key
Site	A known histone PTM is indicated, based on the Brno nomenclature (Turner 2005), by the numbered amino acid residue at which it occurs followed by the abbrevation for its chemical modification (see Modification key).
Model	Refers to the model organism in which a PTM was characterized.
Enzyme	Where known, the histone-modifying enzyme (writer) that transduces a PTM is indicated. Italics specify the valency of modification that an enzyme can catalyze.
Function	The associated biological function of a histone PTM is indicated where known.
Reference	The key primary references where a PTM and/or its function are described are listed.