Double punctuation is used only with abbreviations, quotation marks, run-in side headings, parentheses, and brackets. Difficulty sometimes arises over the order of the punctuation marks when double punctuation is needed.

1. In abbreviations, the period marking the abbreviation comes first and the punctuation mark second.
   
   
2. If the abbreviation comes at the end of the sentence, no final period is needed.
   
   
3. In run-in side heads, the period may be followed by a dash.
   
   
4. If material enclosed in parentheses is not directly related to the statement preceding it and makes a complete sentence, the period goes inside the closing parenthesis and the sentence in parentheses begins with an upper case letter; if it forms part of the sentence, the period goes outside (the same rule applies when using brackets).
   
   For the usage of quotation marks, see the section entitled 'Quotation marks'.