Manuscript Preparation, Copyediting, and Proofreading
Q. When breaking a URL, can a hard return be used? If not, how should it be done? You give examples of broken URLs, but it is not clear how that is done according to a press’s and printer’s requirements.
A. In manuscripts prepared in a word-processing program for print publication, it’s best not to break URLs. The line breaks in your manuscript will not match the ones in the printed product. Moreover, such characters as hard (nonbreaking) hyphens and optional line breaks (also called discretionary line breaks) inserted using a program like Microsoft Word will likely not convert properly to other software platforms like page-layout or typesetting programs. Just make sure that your publisher and compositor are aware of the rules for breaking URLs (see paragraph 14.12 in CMOS 16). Whoever composes pages, then, will use discretionary line breaks and nonbreaking hyphens, as necessary, to ensure that URLs break properly at the ends of lines.