As implemented in the MS-DOS operating system and its successor Microsoft Windows, a / pair—not required in Spanish but needed for Catalan, Portuguese, and French—is typically added, and the use of the acute accent and diaeresis with capital letters (, , , , , ) is supported. Although not needed for Spanish, another dead key with (the grave accent) in lowercase position and (the circumflex accent) in uppercase position was included. Also available is (the "flying point", required in Catalan). To make room for these characters not on the standard English keyboard, characters used primarily in programming, science, and mathematics— and , and , and , and and —are removed, requiring special keystroke sequences to access.