The model contains one compartment called C. There are three species called S1, S2 and S3 and one parameters called p1. 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 defines another (different) local parameter k. Note that these parameters have a scope local to the defining reaction.

The model contains one initialAssignment:

Variable Formula
S1 p1 · 2

Note: SBML's InitialAssignment construct override any declared initial values. In this case the initial value declared for species S1 is consistent with the value returned by the InitialAssignment.

The initial conditions are as follows:

Value Units
Initial amount of S1 0.25 × 10−2 mole
Initial amount of S2 2.0 × 10−2 mole
Initial amount of S3 1.0 × 10−2 mole
Value of parameter p1 1.25 × 10−3 mole
Value of parameter local k 0.75 litre mole-1 second-1
Value of parameter local k 0.25 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) they must be treated as concentrations where they appear in expressions.