Editing for grammar, spelling, punctuation and other mechanics of style; checking for consistency of mechanics and internal consistency of facts; marking head levels and approximate placement of art; notifying designer of any unusual production requirements. May include Canadianizing; metrication; providing or changing system of citations; writing or editing captions and/or credit lines; writing running heads; listing permissions needed and/or obtaining them; providing or editing prelims, back matter, cover copy and/or CIP data. May also include negotiating changes with author.
N.B. "Copy editing" is often loosely used to include stylistic and even structural editing, fact checking and mark-up. It is not so used by the Editors’ Association of Canada.
Definition taken from Editors' Association of Canada.