Return True if Cell's value is different than the default value. Almost every column type have own DefaultValue property of type native to the column.

function IsSet: Boolean; virtual;

Example

NextGrid61.Cell[0, 2].AsInteger := 0; // IsSet return False
NextGrid61.Cell[0, 2].AsString := ""; // IsSet return False

In this example column with Index 0 is Number Column.