We study the set of all m-tuples (λ(1), . . ., λ(m)) of possible types of finite abelian p-groups Mλ(1), . . ., Mλ(m) for which there exists a long exact sequence Mλ(1) → ⋅⋅⋅ → Mλ(m). When m=3, we recover W. Fulton's (Eigenvalues of majorized Hermitian matrices and Littlewood-Richardson coefficients (Special Issue: Workshop on Geometric and combinatorial Methods in the Hermitian Sum Spectral Problem), Linear Algebra Appl. 319(1–3) (2000), 23–36) results on the possible eigenvalues of majorized Hermitian matrices.