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