# 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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# xAxis.tickmarkPlacement

For categorized axes only. If `on` the tick mark is placed in the center of the category, if `between` the tick mark is placed between categories. The default is `between` if the `tickInterval` is 1, else `on`. In order to render tick marks on a category axis it is necessary to provide a tickWidth.