  In the recent paper [1], a new method based on measuring a temperature
correction to a quantum-oscillation frequency was proposed to study an
energy-band dispersion of charge carriers in small Fermi surface (FS) pockets
of crystals. To illustrate their approach, Guo et al. [1] applied it to a
number of materials and, in particular, to the multiband metal LaRhIn$_5$
which, apart from high-frequency oscillations associated with a large FS, also
exhibits the oscillations with the low frequency $F\approx 7$ T. Although the
method of Ref. [1] really detects charge carriers with a linear dispersion, it
does not distinguish between the carriers near a Dirac point and near a nodal
line, since all such quasiparticles disperse linearly. Here we ask what is the
nature of the carriers associated with the frequency $F$ in LaRhIn$_5$ and call
attention to the puzzling origin of this frequency.
