 The main difficulty arises from the ambiguous use of the word amide to mean an acylated (including sulfonylated) amine "or" the anionic form of an amine.Likewise, imide can refer to a bisacylated amine "or" a twice deprotonated amine.Thus, depending on the system used, there is ambiguity as to whether amide or imide is being used to refer to the parent acid or the anion.