When you open a new project in Workflow Designer, two models are automatically created: the Primary model and the Critical Errors model. In an open project in Workflow Designer, these models appears in the project tree structure in the left pane.
You can add other models to your project. Models that you add to a project are called secondary models. Secondary models also appear as items in the project tree structure. Secondary models can work with other models or run independently (depending on their configuration). You can add an unlimited number of secondary models to a project.
Use the Linked Model component to invoke a model from another model. If secondary models are linked to other models with the Linked Model component or the Dynamic Linked Model component, they are called linked models.