Q. Have you established any rules for breaking web addresses at ends of lines? I would be inclined to break at the slash where possible, with no hyphen (keeping the address intact), but what about the “dots”? Example: eic.edu.gov.on.ca/html/dsbmaps.html (I’ve got another one that’s a line and a quarter long!).
A. We recommend breaking before a period and most other marks of punctuation—including a slash (but not a double slash; always break after “http://”). This helps make it clear that the URL has not come to an end. And yes, never add a hyphen to break a URL. For more detailed information, including examples, see paragraph 14.12 in CMOS 16.