Specify a span to visualize data within the specified window or range of values. The span equals the difference between the minimum and maximum thumb values for the visible range on the range slider. It is also possible to have a span equal to zero (both thumbs on the slider are pushed close together), and the range on the range slider is displayed as a single value.
For example, for a 3D layer that shows all the meeting rooms in a multistory building, you'd like to show only the rooms that fit 20 to 30 people. You can set the Minimum Range to 20 and the Span to 10. Only the meeting rooms that meet the range criteria will be displayed in the view. If you increase the Span to 15, you will see the meeting rooms with occupancy between 20 and 35, inclusive. The query used to display the range-enabled data, in this case, is to display data that is greater than or equal to the minimum of the range and that is less than or equal to the maximum of the range.
Configure the range span on the Range tab in the Current Range group. When the range slider is enabled in the map, you can type a value to customize the span. You can also interactively modify the span value by dragging the minimum thumb on the range slider. The values on the slider update and correlate with the values on the Range tab. You can optionally lock the span to prevent you from interactively changing the span from within the range slider.
Tip:
If the span value appears empty, look to see whether either or both the minimum and maximum values are disabled. An arrow icon appears for the disabled state of both the minimum
and maximum 
ranges.