The dialog appears when you click 
button besides the Real Time option in the Bind Data screen of chart in the Web Report Wizard, Insert Chart dialog, or Chart Wizard. It helps you to specify the options of a real time chart. See the dialog.
The following are details about options in the dialog:
Refresh Interval
Specifies the interval that the chart will get data and refresh itself automatically.
Keep Last N Records
Specifies the number of records that will be kept for the real time data on the chart.
Resources
Lists all the available data resources in the dataset currently used by the real time chart.
Adds the selected fields as the unique keys for the real time chart.
Removes the selected unique keys if they are not required.
Unique Key
Lists the fields you add as unique keys for the real time chart, which are used to guarantee there are no two records with the same unique key value in the real time chart.
When a real time chart is specified with unique keys, each time when the chart automatically update itself, the data that has the same unique key values as the previous loaded data records will be filtered and only data with different unique key values will be added to the chart. For example, if you add the field Time as the unique key for a real time chart, when a record for the time 13:04:05 P.M. has already been loaded into the chart, no more records of this time point will be added to the real time chart because they have the same unique key value.
OK
Applies the settings and closes this dialog.
Cancel
Cancels the settings and closes this dialog.
Help
Displays this help document.