Period

The period ``.'' serves four purposes in English: a sentence terminator, an abbreviation mark (``Mr.'') , a decimal point (``3.14''), and one-third of ellipses (``...''). First here's a silly quiz. Complete the sentence with the appropriate punctuation:

The clock read 4:20 p.m., 4:21 p.m., 4:22 p.m

• ...
• ....
• .....

This multipurpose use makes automated parsing nontrivial. However, in LaTeX, one can introduce a macro, \newcommand{\STOP}{.} that will take us back to the telegraph days\STOP It's still a little tricky to end a sentence with an abbreviation, however, perhaps even that can be fixed by something that detects whether the last character was a period\STOP LaTeX already has \ldots for ellipses\STOP

The clock read 4:20 p\abbreviationperiod m\abbreviationperiod, 4:21 p\abbreviationperiod m\abbreviationperiod, 4:22 p\abbreviationperiod m\abbreviationperiod\ldots\STOP