For each orbit of faces of codimension k we give a canonical representative face f_i. The face fk_i is defined by a set of k inequalities of rank k satisfied with equality. A triangular inequality Tr of met_n is represented by a {-1,0,1}-valued vector V of length n with 3 nonzero entries with: Tr_ij = V_i x V_j. The left hand side of Tr is 2 if V is a {0,1}-valued vector and 0 otherwise. +++++ remark ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ the set of all inequalities satisfied with equality by f_i might be larger than k but we show only k facets. This way the codimension is directly readable and the presentation is homogeneous) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -------------- canonical representatives -------------------------- f3_1 1 1 1 0 1 1 0 1 1 0 1 1 f3_2 1 1 1 0 1 1 0 1 1 0 -1 1 f3_3 1 1 1 0 0 1 1 0 1 0 1 1 0 0 1 f3_4 1 1 1 0 0 1 1 0 1 0 1 0 1 0 1 f3_5 1 1 1 0 0 1 1 0 1 0 0 0 1 1 1 f3_6 1 1 1 0 0 1 1 0 1 0 0 0 -1 1 1 f3_7 1 1 1 0 0 0 1 1 0 1 0 0 1 0 0 0 1 1 f3_8 1 1 1 0 0 0 1 1 0 1 0 0 0 0 1 0 1 1 f3_9 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 f3_10 1 1 1 0 0 0 1 0 0 1 1 0 0 -1 0 1 0 1