‘Substantial’ has to be certain.

The words" outward, open, actual, visible, substantial, and exclusive," in connection with a change of possession, mean substantially the same thing. They mean not concealed; not hidden; exposed to view; free from concealment, dissimulation, reserve, or disguise; in full existence; denoting that which not merely can be, but is opposed to potential, apparent, constructive, and imaginary; veritable; genuine; certain: absolute: real at present time, as a matter of fact, not merely nominal; opposed to form; actually existing; true; not including, admitting, or pertaining to any others; undivided; sole; opposed to inclusive.