Source classification method using CuDiDi. Left: sketches of representative light-curve behaviour, which illustrate typical variability patterns for persistent, repeating, and transient sources. Centre: corresponding CDFs. The y-axis shows the cumulative number of counts N, normalised by the total so that each distribution reaches unity. Each CDF is split at the median (0.5) into lower (0–0.5, shaded light grey) and upper (0.5–1.0) halves. The mean values of each half, μ_lower and μ_upper, are indicated. Right: CuDiDi plot showing μ_lower vs. μ_upper for each source. The diagonal band (±0.2 around μ_upper = μ_lower + 0.5) defines the persistent region. Sources above the band are classified as transients, while sources below the band are considered repeating sources. This visualisation shows how CuDiDi uses statistical asymmetries in cumulative flux distributions to separate source classes.