# Using a Modelling Language

Using a modelling language is relatively easy, and requires you to make use of the MainMenu toolbar:

## Loading a Formalism Toolbar

The first step when using a language is to load its associated formalism toolbar by pressing the second button on the MainMenu toolbar. You are presented with a file browser. To load the TrafficLights example, for example:

The toolbar allows you to place instances of classes on the canvas and connect them. For more information, see Formalism Toolbars.

## Opening a Model

To open a model, press the fifth button of the MainMenu toolbar. Opening a model replaces the currently opened model, if any. If there are any unsaved changes in the currently opened model, you will receive a warning.

## Saving a Model

When you are done editing, you can save your model by pressing the seventh button on the MainMenu toolbar. If this is the first time you save a model, you will be presented with a file browser that allows you to choose a name for your model.

Note

Model names need to end with the .model file extension.

## Validating a Model

To validate whether the structure of your model adheres to all constraints defined by the language, press the third-last button. If no message appears, it means all constraints are satisfied. Otherwise, a message appears detailing the constraint that failed. For example: