Table 11: Differences in the abundances of the distinct chemical species used to build the 4 models described in the text. The last column shows the dispersion around the 1:1 relation when comparing the offsets in the indices between galaxies in different environments and the offsets in the indices due to the changes in the chemical species of each model.

Model	[C/H]	[N/H]	[/H]	[G2/H]	[Ca/H]	[Ti/H]	rms
1	+0.05	+0.05	+0.00	+0.00	+0.00	+0.00	0.0066
2	+0.05	+0.05	+0.00	+0.00	+0.00	+0.15	0.0060
3	+0.04	+0.05	+0.00	+0.00	+0.10	+0.15	0.0035
4	+0.04	+0.15	+0.05	+0.05	+0.10	+0.15	0.0034