ICSD-anchored CIF for MgMnGe (Cu2Sb-type, P4/nmm). Z=2. Lattice: a=4.150Å c=6.940Å c/a≈1.67. Validation gates: γ=120°(90° tetragonal), c/a≈1.67, Z=2, stoichiometry MgMnGe satisfied. ICSD prototype: P4/nmm Cu2Sb-type ternary variant.