Sequence providing a detailed view of the evolution of the profiles of the Hα (emission) and Li I (absorption) lines with the variation in the spectral resolution. The first panel (from left to right) corresponds to the original resolution of our FLAMES spectrum of LOri038, a M3 member of C69 (R ~ 8000). In the last panel, we have degraded the FLAMES spectra to a resolution similar to that of our low-resolution campaign (R ~ 800 obtained with the B&C spectrograph). As can be seen in this figure and in Fig. A.2 the lithium equivalent width can be measured down to resolutions of the order of 1250 (for a high S/N as in the case of our spectrum of LOri038). The linestyles and color code are those explained in the text.