The basic idea of Sautrāntika Actualism is that, if “X” is existent, then it must be existent now. Future is not yet arisen and hence non-existent. Past is already extinct and hence non-existent. (This is based on LS Lecture: 47). In other words, it is the idea that all that exist must necessarily be in the present (gzhi grub na da lta ba yin pas khyab).