Model Explorer

The model explorer provides a nested tree view of all the variables,
compartments and flows used in the model. The elements are arranged by
submodel, hierarchically from the top level desktop. In
variable-membership submodels, additional elements used only in those
submodels are also displayed. When a "helper" window requires a variable
to be selected, this action can be performed by clicking on the required
variable in the model explorer.

In: Contents >> Running models >> Working with helpers