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

Reaction Rate
S1 → S2 k2 · S1 · C · time
S2 → S3 k2 · S2 · C · time
S3 → S4 k2 · S3 · C · time

where the symbol 'time' denotes the current simulation time.

Both reactions S1 → S2 and S3 → S4 define a local parameters k2 which has a scope local to the defining reaction and are different from each other and the global parameter k2 used in the reaction S2 → S3.

The initial conditions are as follows:

Value Units
Initial amount of S1 1.0 × 10−4 mole
Initial amount of S2 0 mole
Initial amount of S3 0 mole
Initial amount of S4 0 mole
Value of parameter k2 0.5 second-2
Value of local parameter k2 (R1) 0.7 second-2
Value of local parameter k2 (R3) 1 second-2
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.