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Manuscript Preparation, Copyediting, and Proofreading
Q. Is there a proofreaders’ mark for the number sign? I’m a copy editor and I frequently come across the issue of having to insert a space between a word and a number sign (e.g., between “Employee” and “#”), or I have to insert a space and a number sign. This, obviously, causes some confusion because it looks like I’m asking to have two spaces inserted.
A. When you insert a symbol like that (or a question mark or exclamation mark), you should write a clarification in the margin. Write “set number sign” and circle it next to or above your #. If there’s room somewhere on the page, write out the whole phrase as you want it to appear and draw a circle around it. Note that Chicago style avoids putting a # sign with a number; it’s quite often superfluous.