The model contains one compartment called "compartment". There are four species named S1, S2, S3 and S4 and two parameters named k1 and k2. Compartment "compartment" is 0-dimensional. Both species S1 and S2 are labeled as an SBML boundary species. The model contains two reactions defined as:

Reaction Rate
S1 + S2 → S3 + S4 k1 · S1 · S2
S3 + S4 → S1 + S2 k2 · S3 · S4

The initial conditions are as follows:

Value Units
Initial amount of S1 1.0 mole
Initial amount of S2 1.5 mole
Initial amount of S3 2.0 mole
Initial amount of S4 0.5 mole
Value of parameter k1 0.6 mole-1 second-1
Value of parameter k2 0.13 mole-1 second-1

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.