Hα and X-ray activity index vs effective temperature for the Class III sources (shown with the same plotting symbols as in Fig. 4) compared with two samples of field M dwarfs: for the 10-pc sample from Stelzer et al. (2013) crosses represent stars with measured rotational velocity (small and large symbols for slow and fast rotators, respectively, with dividing line at 3 km s^-1) and plus symbols are stars without vsini data. The mean active SDSS sample from Bochanski et al. (2007) is represented by diamonds; see Sect. 4.1 for details.