The model contains one compartment called C. There are four species called S1, S2, S3 and S 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

Reaction S1 → S3 defines one local parameter k1 and reaction S3 → S2 defines one local parameter k2. These parameters have a scope local to the defining reaction and are different from the global parameters k1 and k2 used in the rules.

The model contains two rules:

Type Variable Formula
Assignment S4 k3 · S1
Rate S2 k2 · S3−k1 · S1

Note that in this case the initial value of 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 × 10−5 mole
Initial amount of S2 1.5 × 10−5 mole
Initial amount of S3 1 × 10−5 mole
Initial amount of S4 undeclared mole
Value of parameter k1 0.015 second-1
Value of parameter k2 0.5 second-1
Value of parameter k3 1.5 dimensionless
Value of local parameter k1 0.01 second-1
Value of local parameter k2 0.4 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.