Schematic light curve diagram (blue solid curve) of a type D WZ Sge-type DN without rebrightening. Thick gray horizontal line represents the quiescent phase brightness. The beginning points of the four phases—rising, plateau, decline, and tail parts—are marked as 1, 2, 3, and 4, respectively. The short blue dashed line is the extension of the decline part to the quiescent magnitude. “D_p” between points 1 and 5 is the outburst duration above the quiescent magnitude.