The model contains one compartment called "compartment". There are four species named S1, S2, S3 and S4 and four parameters named k1, k2, k3 and k4. Species S3 is labeled a SBML boundary condition and is also labeled constant. The model contains four reactions defined as:

Reaction Rate
S1 → S2 k1 · S1 · compartment
S2 → S1 k2 · S2 · compartment
S2 → S3 + S4 k3 · S2 · compartment
S3 + S4 → S2 k4 · S3 · S4 · compartment

The initial conditions are as follows:

Value Units
Initial amount of S1 1.0 × 10−4 mole
Initial amount of S2 2.0 × 10−4 mole
Initial amount of S3 0 mole
Initial amount of S4 0 mole
Value of parameter k1 0.75 second-1
Value of parameter k2 0.25 second-1
Value of parameter k3 0.4 second-1
Value of parameter k4 0.1 litre mole-1 second-1
Volume of compartment "compartment" 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.

Note: The test data for this model was generated from an analytical solution of the system of equations.