Aramaic has two proper tenses: perfect and imperfect. These were originally aspectual, but developed into something more like a preterite and future. The perfect is unmarked, while the imperfect uses various preformatives that vary according to person, number and gender. In both tenses the third-person singular masculine is the unmarked form from which others are derived by addition of afformatives (and preformatives in the imperfect). In the chart below (on the root כת״ב K-T-B, meaning "to write"), the first form given is the usual form in Imperial Aramaic, while the second is Classical Syriac.