What is open punctuation, standard punctuation, and closed punctuation?
see answer below
in an open punctuation, it marks after the greeting or complimentary closing of a business letter. standard punctuation are stuff like comma, semicolon and colon. you use closed punctuation with abbreviations, introductory greetings or a letter closing. an example would be: when you write “Dear Mr. Bob,” or sign a letter “Sincerely,” you'd use a comma after both phrases, different than open punctuation.