# 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.

# navigator.xAxis.dateTimeLabelFormats

For a datetime axis, the scale will automatically adjust to the appropriate unit. This member gives the default representations used for each unit. For easier data interpretation, `hour`, `day`, `month` and `year` units can be used and formatted as boundary tick values. Check boundaries map below to see where to format boundary ticks on given main time units.

        baseUnit: boundaryUnit
        ----------------------
        millisecond: 'hour',
        second: 'hour',
        minute: 'hour',
        hour: 'day',
        day: 'month',
        week: 'month',
        month: 'year',
        year: 'year'

For an overview of the date time label formats configuration, see dateFormat.

Defaults to:

    {
        millisecond: { main: '%[HMSL]' },
        second: { main: '%[HMS]' },
        minute: { main: '%[HM]' },
        hour: { main: '%[HM]', boundary: undefined },
        day: { main: '%[eb]', boundary: '%[eb]' },
        week: { main: '%[eb]' },
        month: { main: '%[bY]', boundary: undefined },
        year: { main: '%Y', boundary: undefined }
    }