The model contains one compartment called C. There are four species called S1, S2, S3 and S4 and two parameters called k1 and k2. The model contains two reactions defined as:

Reaction Rate
S1 + S2 → S3 + S4 k1 · S1 · S2 · C
S3 + S4 → S1 + S2 k2 · S3 · S4 · C

The model contains one event that assigns values to both species S1 and S4:

?(t_c)
Trigger Delay Assignments
Event1 S4 > S2 S1 → 2 × 10−1
S4 → 0.5 × 10−1

The initial conditions are as follows:

Value Units
Initial amount of S1 1.0 × 10−1 mole
Initial amount of S2 1.0 × 10−1 mole
Initial amount of S3 2.0 × 10−1 mole
Initial amount of S4 1.0 × 10−1 mole
Value of parameter k1 0.75 × 101 litre mole-1 second-1
Value of parameter k2 0.25 × 101 litre mole-1 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.