# 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.xrange.dataLabels.nullFormat

Format for points with the value of null. Works analogously to format. `nullFormat` can be applied only to series which support displaying null points. `heatmap` and `tilemap` supports `nullFormat` by default while the following series requires [#series.nullInteraction] set to `true`: `line`, `spline`, `area`, `area-spline`, `column`, `bar`, and `timeline`. Does not work with series that don't display null points, like `pie`.