Example of the plots that we used to classify the pulsators based on their relative Fourier parameters, in this case RRc variables (blue). The background is composed of the known OGLE variable stars (except the Cepheids), as in Fig. 5 but now coloured in shades of grey. The dots denote the newly found variables. The crosses mark the ones that turned out to be the results of contamination by known close variables (listed in Table 1).