8 Multivariate classification

S stars from the Henize sample have been classified into several groups using a multivariate classification scheme combining the most relevant parameters described in the previous sections. The clustering algorithm is described in Paper III. Two different clustering have been performed, resulting in a classification in either two or six groups of S stars. The cluster assigned to a given star is listed in Cols. C₂ and C₆ of Table 6, corresponding to the 2- and 6-clusters classifications, respectively. The last column labelled $C_{\rm f}$ lists the assignment finally retained, as either intrinsic ("i'') or extrinsic ("e'').