Example X-ray light curves and their classification with CuDiDi. Left column: total counts binned at 1 ks for visual clarity and normalised in time for three representative sources per row. Transient sources are shown in the top row, and non-transient sources in the bottom row. Middle column: corresponding CDFs, obtained from the light curves with 1 s bins, normalised to unity. The shaded grey area indicates the lower half (0–0.5) of the cumulative fraction. Right column: CuDiDi diagram showing μ_lower vs. μ_upper, where μ_lower and μ_upper denote the mean values of the lower and upper halves of the cumulative distributions, respectively. Transient sources are marked as squares, and non-transient sources are shown as circles. The shaded green band indicates the transient region, defined as +0.2 above the diagonal μ_upper = μ_lower + 0.5. Sources in this region are classified as transients, while those below fall into the non-transient category. The colours and line styles in all panels indicate observation ID: solid green line = 7048, dashed blue line = 16174, dotted orange line = 20120. This demonstrates how CuDiDi captures the distinct variability patterns of transient and non-transient sources.