Practice Exercise for Proofreaders'/Teachers' Marks Sep 22, 2007Practice Exercise for Proofreaders' Marks and Teachers' Marks. Proofreaders' Marks Practice B: Campus Email Memo. Colleagues, We are in the process of developing a major in Popular Media Studies as an option of our multimedia education baccalaureate program. As you know, to develop an option, at least 50% of the courses need to be in common. PROOFREADERS' MARKS AND PROOFREADING SYMBOLS - EditFast Sep 12, 2016Local, in-house style guides may vary from company to company with additional marks specific to that industry but the proofreading symbols below are common to all. If you wish to be an all-encompassing editor or proofreader, ready for any situation, you should know these proofreaders' marks and be able to use them with ease.