Modification key
ac	acetylation	mal	malonylation
ar1	mono-ADP-ribosylation	me1	monomethylation
bio	biotinylation	me2	dimethylation
but	butyrlyation	me3	trimethylation
cit	citrullination	og	O-GlcNAcylation
cr	crotonylation	oh*	hydroxylation
for	formylation	ox*	oxidation
gt*	glutathionylation	ph	phosphorylation
hib	2-hydroxyisobutyrylation	su	SUMOylation
iso	isomerization	ub	ubiquitination

* XYZ modifications are known to occur on histone proteins but have not been included in these tables at individual amino acid residues.