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

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

The model contains two events that assign values to species S2 and S1:

| Trigger | Delay | Assignments
Event1 | lessthan(S1, 0.6) | − | S2 = 1.5
|  |  | S1 = add(k3, k4)

Both the event trigger and assignment use functionDefinitions defined as:

Id | Arguments | Formula |  | add | x, y | x + y
lessthan | x, y | x < y

The initial conditions are as follows:

| Value | Units
Initial amount of S1 | 1.0 | mole
Initial amount of S2 | 2.0 | mole
Initial amount of S3 | 1.0 | mole
Value of parameter k1 | 0.75 | litre mole-1 second-1
Value of parameter k2 | 0.25 | second-1
Value of parameter k3 | 0.5 | mole litre-1
Value of parameter k4 | 0.5 | mole litre-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.