The model contains one compartment called C. There are four species called S1, S2, S3 and S 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. Reaction S3 → S1 + S2 also defines one (different) local parameter k. Both of these parameters have a scope local to the defining reaction.

The model contains one rule:

Type Variable Formula
Assignment S4 k · S2

Note that in this case the initial value of species S4 has not been declared and must be calculated using the assignmentRule.

The initial conditions are as follows:

Value Units
Initial amount of S1 1 × 10−5 |mole | |Initial amount of S2 | 1.5 \x 10-5 |mole | |Initial amount of S3 | 1 \x 10-5 |mole | |Initial amount of S4 | undeclared |mole | |Value of parameter k | 1.5 |dimensionless | |Value of local parameter k | 1.5 \x 10^4 |litre mole−1^ second−1^ | |Value of local parameter k | 5 |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.