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 -------------------------- f1_1 1 1 1