The model contains one compartment called C. There are three species called S1, S2 and S3 and three parameters called k1, k2 and p1. Compartment C is 0-dimensional. The model contains two reactions defined as:

Reaction Rate
S1 + S2 → S3 k1 · S1 · S2
S3 → S1 + S2 k2 · S3

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 × 10−4 mole
Initial amount of S2 2.0 × 10−4 mole
Initial amount of S3 1.0 × 10−4 mole
Value of parameter k1 0.75 mole-1 second-1
Value of parameter k2 0.25 second-1
Value of parameter p1 1.25 × 10−5 mole

In this example, the compartment has its spatialDimensions attribute set to zero, i.e., it represents a point and therefore cannot have size or units. The species values must be treated as amounts and not concentrations.