Table A.1: Lick indices for M 31 globular clusters from new observations (Sect. 3.1).
Table A.2: Lick indices M 31 globular clusters taken from literature sources and reported into the T98 system (Sect. 3.2).
Table A.3: Metallicities for M 31 globular clusters.
During the first phases of the present study we considered the largest set of Lick indices to search for the best candidates to be used as metallicity indicators for our scale. As a useful tool for this choice we computed the matrix of Spearman rank correlation coefficients (Press et al. 1992) for a set of indices in the T98 system and metallicity for Galactic GCs. Since this matrix can be of general interest, we present it here as Table B.1 below. It must be recalled that these correlations coefficients are computed using a sample of nearly-uniformly old stellar populations, so it refers only to classical old globulars.
Table B.1: Spearman rank correlation coefficients.