The model contains one compartment called C. There are four species called S1, S2, S3 and S4 and three parameters called k1, k2 and k3. The model contains two reactions defined as:

Reaction Rate
S1 → S3 k1 · S1 · C
S3 → S1 k2 · S3 · C

The model contains two rules:

Type Variable Formula
Assignment S4 multiply(k3, S1)
Rate S2 k2 · S3−k1 · S1

The assignmentRule applies the functionDefinition defined as:

Id Arguments Formula
multiply x, y x · y

Note that in this case the initial value declared for species S4 is consistent with the value calculated by the assignmentRule.

The initial conditions are as follows:

Value Units
Initial amount of S1 1 × 10−5 mole
Initial amount of S2 1.5 × 10−5 mole
Initial amount of S3 1 × 10−5 mole
Initial amount of S4 1.5 × 10−5 mole
Value of parameter k1 0.015 second-1
Value of parameter k2 0.5 second-1
Value of parameter k3 1.5 dimensionless
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.