xxllnc Expertsystemen: first steps
xxllnc Expertsystemen is the modelling environment where you will develop your own decision tree model. In these tutorials we will refer to xxllnc Expertsystemen as Studio. You can always press [F1] to open the help files. The Studio will guide you to the right web page depending on which window you have opened.
A model
All models consist of nodes connected to each other with connections, and graphs, which are groups of connected nodes. Models are made interactive with actions, such as questions and texts. All these elements together - graphs, nodes, connections and actions - form a decision tree model.
As for now, you might wonder how to go about using these components to create a decision tree model. This will be covered extensively after we discuss the basic navigation in xxllnc Expertsystemen.
Studio Layout
The Studio is the modelling environment of xxllnc Expertsystemen. This is where you will be developing your decision tree models. After having downloaded the Studio from here, open the Studio and you will see the following screen the first time you open the software:
The Studio is divided into four panels and a menu. These are the sections that you will be using the most:
- Graph panel: the middle panel is where you will create and structure your model;
- Actions panel: this panel is where you view, add and edit actions of a node;
- Interface panel: this panel shows a small preview of your model;
- Text fragments panel: this panel shows all the text fragments that you have added to your model.
Via the top menu (the ribbon) you have access to all actions you can perform. The different items are grouped by topic, such as the layout or the graph.
Nodes
From all the different items that you can add, nodes are the components that define the underlying structure of a decision tree model. Every node defines a new decision point in your graph.
When you open the Studio for the first time, there is already a node called ‘start’. To add a new node, make sure the node ‘start’ is selected by clicking on it, go to the graph menu in the ribbon and click 
New node.
In the window that pops up, you can enter the node name. Be sure to give the node a name that covers what you want to place in that node.
When you add a node, a connection (line) between the node you selected and the one you just added is created automatically. It is also possible to connect multiple nodes to the same node. To do so, click on the node ‘start’ again and add another node.
Connections
Connections show the flow of your model: they show all the paths through your model that are possible. The path that a user goes through is dependent on the decisions a user makes in the nodes. For example, answering a question with ‘yes’ may go through another path than answering it with ‘no’.
Every time you add a new node, a connection is automatically added in the Actions panel. Connections are represented by arrows between nodes. The arrows also show the flow of the model.
Saving your decision tree model
When working on a decision tree model, it is useful to save it often. You can do this by pressing [Ctrl+S] or by going to File in the top menu and clicking on 
Save.
Save it in a convenient place where it’s easy to locate. It’s also good practice to create a separate folder for each model. For more about saving, see Saving and running your model