All underlining, notes to copy editors, etc. Make these marks in red pencil or some vividly colored ink. A typewritten underline might be printed as a bar under a variable and not as an italic variable. Please differentiate between math symbols in the text and mere abbreviations that are not math symbols. Write a note in the margin to avoid confusion.
Printers sometimes have trouble with upper versus lower-case characters.
Please make a note in the margin whenever such characters appear that are not completely clear without reading the paper. Italicize all variables in equations and in the text. Underline all variables in the text in red or other vividly colored ink. On a page with a great many variables, do not underline, but place a note to the copy editors at the top, indicating that all variables on that page are to be italic. If there are any abbreviations or other expressions on the page that are to be left Roman, circle them and indicate in the note that the circled material should remain Roman.