# Understanding the Span Model

This topic explains about the Span model used in Spread for ASP.NET. Learn more in documentation.

## Content

The span model includes the objects needed to handle cell spans and automatic merging of cells. Refer to the Cell class, [ColumnSpan](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Cell.ColumnSpan.html) and [RowSpan](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Cell.RowSpan.html) properties.
To use the underlying span model, use the [Add](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.Add.html), [Clear](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.Clear.html), and [Remove](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.Remove.html) methods of the span model. Refer to the [Assembly Reference](/spreadnet/docs/latest/online-asp/overview/assembly-reference) for more information on the span model in general and to the [DefaultSheetSpanModel](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.html) methods in particular.
The default implementation of the span model ([DefaultSheetSpanModel](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.html)) uses an array to store the cell spans. If there are a modest number of spans in the sheet (for example, a thousand or less) then the default implementation is responsive. If there are a very large number of spans in the sheet (for example, a hundred thousand or more) then the default implementation slows dramatically.
In scenarios where you have a very large number of spans that repeat on a regular interval, you should consider writing a custom span model. By writing a custom span model, you can significantly increase the speed and decrease the memory usage.

## See Also

[Add Method](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.Add.html)
[Clear Method](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.Clear.html)
[Remove Method](/spreadnet/api/latest/online-asp/FarPoint.Web.Spread/FarPoint.Web.Spread.Model.DefaultSheetSpanModel.Remove.html)