Comparison of the experimental data sets of various relaxors for h00 and hh0 spots. The system label (see text), hkl for central point and probe (X for X-rays or N for neutrons) are indicated in the individual panels. 1 and 8 refer to Hiraka et al. (2004); 2 and 9 refer to Xu, Zhong et al. (2004); 3 and 10 (integration thickness ±0.005 r.l.u.), 4 and 11 (integration thickness ±0.2 r.l.u.) refer to this work; 5 and 12 refer to Welberry (2008); 6 and 7 refer to Cervellino et al. (2011a,b); 7 refers to Vakhrushev et al. (2005).