  In the Lagrangian field theory, one gets different identities for different
stress energy-momentum tensors, e.g., canonical energy-momentum tensors.
Moreover, these identities are not conservation laws of the above-mentioned
energy-momentum tensors in general. In the framework of the multimomentum
Hamiltonian formalism, we have the fundamental identity whose restriction to a
constraint space can be treated the energy-momentum conservation law. In
standard field models, this appears the metric energy-momentum conservation
law.
