An editor edits the content to make it free of grammar and style errors. Grammar errors include subject–verb concord, word usage, prepositional/adverbials, parallelism, article usage, pronoun antecedent, active and passive constructions, parenthetical constructions, restrictive and non-restrictive elements, apposition, punctuation and so on. Correcting the style errors include setting the content according to the preferred style of the customer, including citations to references, figures, tables, and other elements of text, bibliography/references; correcting the content for consistency according to the US or UK English and so on. The editors make sure that the content is consistent in capitalization, italicization, variables, scientific notations, tables, figures, and schemes, structuring and tagging of the chapters based on style sheets, and editing equations using Math Editor.