Distribution of log period change rate for first crossing candidates in class 2 sample as a function of log pulsation period. The scatter points represent different samples: LMC F (red), LMC 1O (green), SMC F (purple), and SMC 1O (gray). The theoretical regions for the first and third crossings, as described by Turner et al. (2006), are indicated by black dashed and green dot-dashed lines, respectively. Two black plus symbols represent the first crossing candidates identified by Rodríguez-Segovia et al. (2022).