IFERROR returns a value you specify if a formula evaluates to an error; otherwise, returns the result of the formula. A list of the supported functions is available at http://docs.telerik.com/devtools/document-processing/libraries/radspreadprocessing/features/formulas/functions This function can be implemented as a custom function. Check the following resources for more details on how to achieve that: - http://docs.telerik.com/devtools/document-processing/libraries/radspreadprocessing/features/formulas/custom-functions - https://github.com/telerik/xaml-sdk/tree/master/Spreadsheet/WPF/CustomFunctions