By default, the UserData property is empty. The UserData property stores additional data associated with the serie. It can be used to store custom or additional information for a serie, such as descriptions, identifiers, or metadata. The UserData property can also be accessed programmatically to perform custom logic, filtering, or labeling based on the serie’s associated information. You can use the Def(exSerieUserData) property to define a default extra-data that will be automatically assigned to multiple newly created series.

The "user" keyword retrieves the actual value of the UserData property and can be used in ToolTipFormat or ValueFormat expressions to display this information in tooltips or directly on the serie’s data values, allowing for meaningful labels and enhanced data presentation.