It is shown that, by the possible use of circuit equivalences, circuits satisfying rather light assumptions possess the semistate description

where

input,

output,

semistate, and

are constant operators. The semistate can be chosen as tree branch voltages and link branch currents; a determination of consistent initial semistates is given which stems from a forward stepping solution equation. An appropriate reduction with attendant signal-flow graph for design is obtained in the linear time-invariant case.