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

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

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# plotOptions.gantt.tooltip.clusterFormat

The HTML of the cluster point's in the tooltip. Works only with marker-clusters module and analogously to pointFormat.

The cluster tooltip can be also formatted using `tooltip.formatter` callback function and `point.isCluster` flag.