to these results. For the 2 p$_{j}$ states, the correction is much smaller and, for our purpose, it is sufficient to use the αZ -expansion [73] with the boundaries for the higher-order remainder ± 2 α $^{2}$( αZ ) $^{6}$/ (8 π $^{2}$). As one can see from the tables, the total theoretical results agree well with the experimen- tal data. Compared to the experimental accuracy, the theoretical one is generally better, al- most the same in the cases of argon ( Z = 18) and iron ( Z = 26), and worse for neon ( Z = 10) and scandium ( Z = 21, the 2 p$_{3}$$_{/}$$_{2}$ − 2 s transition). For middle- Z ions, the leading theoretical uncertainties arise from the higher-order screened QED and the electronic-structure con- tributions. For Z greater than 40 the uncertainty due to the two-loop one-electron QED corrections becomes also considerable. We conclude that the present status of the theory and experiment for middle- Z Li-like ions provides a test of QED on a level of a few tenths of a percent. Further improvements of the theoretical predictions can be achieved by calculating the screened QED corrections of the second order in 1 /Z and the three-photon exchange QED corrections. 31