If you are not responsible for producing final copy and have to indicate your revisions on the draft, you must use proofreader’s marks to help the typesetter or other specialist understand and make the changes required.
If you are proofreading typeset material, you must distinguish between typesetting errors and changes you or the author have decided to make. The mark “AA” (author’s/editor’s alterations) indicates such alterations. Copy should be at least double-spaced within a 4-cm margin around the text. Proofreader’s marks can be made in red ink in the right-hand space; editing notes can be made in another colour in the left-hand space.