P9-c: Conventional abbreviations

P9-cUse BC, AD, a.m., p.m., No., and $ only with specific dates, times, numbers, and amounts.

The abbreviation BC (“before Christ”) follows a date, and AD (“anno Domini”) precedes a date. Acceptable alternatives are BCE (“before the common era”) and CE (“common era”), both of which follow a date.

40 BC (or 40 BCE) 4:00 a.m. (or AM) No. 12 (or no. 12)
AD 44 (or 44 CE) 6:00 p.m. (or PM) $150

Avoid using a.m., p.m., No., or $ when not accompanied by a specific numeral: in the morning (not in the a.m.).