Period-radius relation. LMC objects are plotted as open squares, SMC objects are filled squares. Blue symbols indicate the six CCs in EBs. Outliers removed from the fit are marked by a red cross and some are identified. The black line indicates the best fit (excluding the outliers) to the complete MC sample. Fits to the LMC and SMC stars separately are given in the text. The blue line gives the PR relation for MW CCs from G20.