Q. Regarding the citation of specific times in videos and the like, CMOS 14.58 provides this example (for an audiobook): “at 3 hr., 14 min.” But many sources use the format HH:MM:SS. I’m just wondering what the preferred Chicago-style formatting for such times is, and whether the “at” should be included, or only where the presence of an audio or video duration may threaten ambiguity, similar to the inclusion/exclusion of “p.” and “pp.” mentioned at CMOS 14.50.
A. You can usually use the format shown for the time in the source itself, but doing so is not a requirement. For example, you can record “03:14:00” instead of “3 hr., 14 min.” if that’s how the timing displays in whatever platform you’re using to consult the cited source. The former is useful if you know that others will find the same thing when they consult the source (and it’s less awkward for timings with hours, minutes, and seconds), but the latter can be easier to interpret.
As for “at,” it is usually good to add that word before a specific time (as in a note) so that it doesn’t get mistaken for a duration or length. But if you cite a range, you can omit “at.” Instead, use an en dash or “to,” as in “03:14:00–03:19:00” or “3 hr., 14 min. to 3 hr., 19 min.” (note the absence of a comma after “14 min.”; the comma that follows “3 hr.” stands in for the word “and” rather than setting off “14 min.”). And if you spell out “to” rather than using a dash, you don’t usually need to write “from” before the range but may add it for clarity (see also CMOS 9.62).