Criteria for spectral classification of cool stars using high-resolution spectra

We have compiled a large number of optical spectra of cool stars taken with different high-resolution echelle spectrographs (R ≃ 40 000). Many of those are available as spectral libraries (Montes et al. 1997, 1998, 1999, http://www.ucm.es/info/Astrof/invest/actividad/spectra.html).