# Welcome to the Highcharts Gantt JS (gantt) Options Reference

These pages outline the chart configuration options, and the methods and properties of Highcharts objects.

Feel free to search this API through the search bar or the navigation tree in the sidebar.

# series.gantt.tooltip.clusterFormat

The HTML of the grouped point's nodes in the tooltip. Works only for Treemap series grouping and analogously to pointFormat.

The grouped nodes point tooltip can be also formatted using `tooltip.formatter` callback function and `point.isGroupNode` flag.