alters the derived spectral type by $<$ 0.5 types [@bejar01]. Thus, we do not expect these spectra to be significantly affected by reddening. The same conclusion was made in the case of the Taurus association objects. While the WK index is sensitive to reddening, and therefore should be dereddened where possible, we have used it as a check on the spectral type derived from the more accurate QK index. We did not re-examine the spectral types of the field dwarfs in our dataset, as our spectral indices are only applicable to young objects. Our results are shown in Table 4.

Spectral types were rounded to the nearest 0.25 subtype (which is the practice in the Luhman system). To assign a spectral type, we took the mean of the spectral types derived using the WK and QK indices. To determine the uncertainties in spectral types, we first measured the scatter in the fits to the WK and QK indices in the M8 to M9.5 interval in W09. This was added in quadrature to the mean average difference (0.3 sub-types) derived from the difference between the WK-based and QK-based spectral types, averaged over the 5 objects in this spectral type interval. Uncertainties 