Indefinite-Metric Quantum Field Theory of General Relativity. X ---Sixteen-Dimensional Superspace---
The sixteen-dimensional superspace structure of the manifestly-covariant canonical formalism of quantum gravity is investigated in detail. The field equations and the equal-time (anti-) commutation relations are shown to be expressible in the sixteen-dimensional form. The sixteen-dimensional Poincaré-like superalgebra found previously is rederived in a unified way. It is shown that this superalgebra is simulated by a system of an idealized angular supermomentum and an idealized supermomentum, where the former is expressed as an antisymmetric product of the latter and an idealized position supervector.