Reserved words are part of the Pascal language, and cannot be redefined. They will be denoted as this throughout the syntax diagrams. Reserved words can be typed regardless of case, i.e. Pascal is case insensitive. We make a distinction between Turbo Pascal and Delphi reserved words, since with the -So switch, only the Turbo Pascal reserved words are recognised, and the Delphi ones can be redefined. By default, Free Pascal recognises the Delphi reserved words.