The model contains one compartment called C. There are three species called S1, S2 and S3 and two parameters called k1 and k2. The model contains one reaction defined as:

Reaction Rate
S1 → S2 C · k2 · S1

The model contains one rule which assigns value to species S3:

Type Variable Formula
Assignment S3 k1 · S2

In this case the initial value for species S3 must be calculated by the assignmentRule. Note that since this assignmentRule must always remain true, it should be considered during simulation.

The model contains one event that assigns a value to species S2:

Trigger Delay Assignments
Event1 S1 < 0.25 1 S2 = 0.75

The initial conditions are as follows:

Value Units
Initial amount of S1 1 mole
Initial amount of S2 0 mole
Initial amount of S3 undeclared mole
Value of parameter k1 0.75 dimensionless
Value of parameter k2 2.5 second-1
Volume of compartment C 2.5 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.