It is shown that some operators in quantum mechanics have hidden structures that\nare unobservable in principle. These structures are based on a supersymmetric\ndecomposition of the momentum operator, and a nonassociative decomposition of\nthe spin operator.
Operational decomposition was introduced in the preceding paper as the process through which the latent structure is operationally assigned to the observable and hidden domains under a given interaction. However, the condition under which this operational assignment becomes established has not yet been clarified. In this paper, we propose that observation induces operational decomposition. Observation is treated as the operational interaction through which the assignment of the latent structure to the observable and hidden domains becomes established, rather than as a process of information acquisition. From the observational perspective, this principle corresponds to the previously introduced statement that measurement grants accessibility. These two principles are interpreted as complementary descriptions of the same operational interaction, viewed respectively from structural and observational perspectives. The present work thereby clarifies the conceptual role of observation in establishing operational decomposition while intentionally leaving its detailed dynamical mechanism outside the scope of the paper.