There are various manuals of style in use, but most fiction editors follow the Chicago Manual of Style. Journalists tend to stick to the AP Manual of Style, unless their publication has it's own as is the case with The New York Times. I was introduced to my very first style manual as a teenager, and was always quite captivated by the proofreader's marks. Were you? In fact, I still look for replacement dictionaries that contain a style manual and proofreader's symbols. Wouldn't buy one without. How do you feel about proofreader's marks? Or do you prefer your editing to come in the comments section of MSWord? Or some other format?