The model contains one compartment called C. There are four species called S1, S2, S3 and S4 and one parameter called k. The model contains one reaction that has a kinetic law that defines third order mass action kinetics with three reactants (as referenced by SBO:0000061):

Reaction Rate
S1 + S2 + S3 → S4 k · S1 · S2 · S3 · C

The initial conditions are as follows:

Value Units
Initial amount of S1 1.0 mole
Initial amount of S2 0.5 mole
Initial amount of S3 0.75 mole
Initial amount of S4 0 mole
Value of parameter k 0.8 litre2 mole-2 second-1
Volume of compartment C 1 litre

The species values are given as amounts of substance to make it easier to use the model in a discrete stochastic simulator, but (as per usual SBML principles) their symbols represent their values in concentration units where they appear in expressions.