The T4 API provides chart data in Tick or Bar format. Bar data contains bars with Open, High, Low, and Close prices as well as Volume traded for 1 Day, 1 Hour, 1 Minute, or 1 Second intervals. You should generally request the largest bar size you need for your application for improved performance and reduced network bandwidth.
The API can also provide chart data restricted to a particular trading session. This is accomplished by supplying the start and end times of the session you are interested in to the chart data request.