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Adds and removes the comment character, an apostrophe, for each line of a selected block of text. If you do not have text selected and you choose the Comment Block or Uncomment Block command, the comment character is added or removed in the line where the pointer is located.
Comment Block
Adds the comment character to each line of a selected block of text.
Toolbar button: .
Uncomment Block
Removes the comment character from each line of a selected block of text.
Toolbar button: 
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