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 two reactions defined as:

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

Reaction S1 + S2 → S3 defines one local parameter k which has a scope local to the defining reaction. Reaction S3 → S1 + S2 defines another (different) local parameter k.

The model contains one rule:

Type Variable Formula
Assignment S4 multiply(k, S2)

The model contains one FunctionDefinition defined as:

Id Arguments Formula
multiply x, y x · y

Note that in this case the initial value of the species S4 is not explicitly declared and must be calculated by the AssignmentRule.

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 1.5 × 10−4 mole
Initial amount of S4 undeclared mole
Value of parameter k 0.75 dimensionless
Value of local parameter k (R1) 0.75 × 104 litre mole-1 second-1
Value of local parameter k (R2) 0.25 × 10−2 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.