Marks of punctuation are used for the purpose of making the meaning of sentences unmistakable. It is not sufficient that sentences be grammatically correct, clear, and vigorous; they must also be perfectly punctuated if their meaning is to be unmistakable. A writer must, therefore, observe the rules of punctuation if his writing is to be intelligible.
800. Use a period (.) at the end of declarative and of imperative sentences.
801. Use a period after every abbreviation.
Right. Mr. C. S. McIntyre of the C. R. I. and P. Ry. Co. received a ten per cent increase.
Right. The editors, reporters, feature writers, etc., and the printers, advertising solicitors, circulation men, etc., of the Springfield (Mass.) Republican are all able men.
802. Never use a period at the end of an incomplete sentence element.
Illiterate. After the sun had set. We went home.
Correct. After the sun had set, we went home.
803. Use a question mark (?) at the end of a direct question.
804. Use a question mark, sparingly, to indicate doubt. In this instance the question mark should be enclosed within parentheses.