Period–amplitude diagram, in logarithms, of all periodic variables. Multiple periods of a same star are connected with straight lines. Colors indicate the group to which the period belongs, coded as in Fig. 10 except for group 5 which is plotted in small gray points instead of black. The X-axis range has been truncated at 7 d for sake of clarity. Only two stars fall outside this range, stars 349 and 1428 with P = 61.5 and 888 d, respectively, both belonging to group 5.