Before revision: Just as early automobiles lacked speedometers, radios, and air conditioners which later became standard, more and more optional software features became standard features in every OS package , although some applications such as database management systems and spreadsheets remain optional and separately priced .
After revision: Just as early automobiles lacked speedometers, radios, and air conditioners which later became standard, more and more optional software features became standard features in every OS package .