# 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.

# yAxis.dateTimeLabelFormats.day.boundary

Label format that should be used when a tick is a boundary tick, e.g. start of day, start of year, etc.