Let’s talk time. Into every writer’s life, time notation must come. And according to grammar purists, there a few points to consider—literally.
- Dots or no dots? The answer here is yes. If you use AM or PM, you do not need periods. If you use p.m. or a.m., you do. Take your pick—unless your editor prefers one in particular.
- What to do with noon and midnight? Technically, you could write 12:00 PM or 12:00 AM, but some will quibble with you. (They’ll send you nasty emails—you know who you are—about why those times can’t possibly exist.) Avoid the issue by using 12:00 noon or just noon and 12:00 midnight or just midnight.
- How to write out times? There’s no strict rule on this, but I recommend going with longhand on times just to make sure there’s no confusion. Write out “three o’clock” or “3:00.”
- What about years? Because of the history of the Western calendar, writing out years can be—well—odd. For most of us, the correct method is to use BC after the date and AD before (12 BC and AD 1066)—or nothing at all for most AD dates. There’s also the lesser used BCE and CE, both of which go after the date (12 BCE and 1066 CE). Note that there are no periods in any of those (pretend like you didn’t see the Wikipedia entry on this). Also, some style guides prefer that you use small caps, but this is cumbersome on the Internet, which is why you rarely see it that way.