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We use published OGLE LMC/SMC data to present comprehensive Period-Color (PC)and Amplitude-Color (AC) relations for both fundamental and overtone stars. Forfundamental mode stars, we confirm earlier work that the minimum lightextinction corrected PC relation in V-I has a shallow slope but withconsiderable scatter (LMC: $[0.093 \pm 0.019]$ with a standard deviation aboutthis line of 0.116, SMC: $[0.055\pm0.058]$ with a standard deviation about thisline of 0.099). We note the high scatter about this line for both the LMC andSMC: either there is some source of uncertainty in extinction or some otherphysical parameter is responsible for this dispersion. We compare with previousresults and discuss some possible causes for this scatter. In contrast, RRcovertone stars do not obey a flat PC relation at minimum light (LMC: $[0.604\pm 0.041]$ with a standard deviation about this line of 0.109, SMC: $[0.472\pm 0.265]$ with a standard deviation about this line of 0.091). The fact thatfundamental mode RR Lyrae stars obey a flat relation at minimum light andovertone RR Lyrae stars do not is consistent with the interaction of thestellar photosphere and hydrogen ionization front. We compare these resultswith PC relations for fundamental and first overtone Cepheids. The fact thatthe PC relations change significantly as a function of phase indicates stronglythat Cepheid and RR Lyrae relations can only be understood at mean light whentheir properties as a function of phase are determined.

Period-Color and Amplitude-Color Relations for RR Lyraes