Projection of processes with orthogonal increments and subordinated processes

Second-order random processes are considered as curves in a Hilbert space ? of random variables ξ with Eξ=0, E∣ξ∣²<∞. Processes which are a projection of a given process x(t) with orthogonal increments on some subspaces of ? are considered. Processes subordinate to x(t) are also considered.