L-Malic Acid Impurity A (As per 34.4 EP Monograph), (2E)-2-Butenedioic Acid, (2E)-But-2-enedioic Acid, (E)-2-Butenedioic Acid, trans-1,2-Ethylenedicarboxylic Acid, trans-2-Butenedioic Acid, trans-Butenedioic Acid; 2-(E)-Butenedioic Acid, (E)-Butenedioic Acid, Allomaleic Acid.