Common mistake, but still--a mistake.
There is no such thing as 12am; nor 12pm. There are noon and midnight. These nice little words are so useful, and so neglected, in favor of AM and PM, though those terms are simply wrong. They leave the matter uncertain, ambiguous. They could intend either noon or midnight. You have to sort it out with whoever issued the time statement, to find out which way they mean it. Maybe it isn't obvious. Maybe it isn't how you understand the usage of the terms. For certain, it is wrong. WRONG, I tell... Sign in to see full entry.