Stars originally classified as pure PC. There are stars from our sample in the top panels. The middle panels show OGLE-III data demonstrating that in long-enough data sets (original classification comes from OGLE-II data with three-times shorter time span) the stars could be classified as BL stars, not pure PC stars. The bottom panels show two stars that clearly show amplitude modulation with periods shorter than 2/3TS suggesting classification as BL+PC, not pure PC. The scales of the axes are the same as in Fig. 3.