API Reference / ExcelSaveDiagnosticsAPI ReferenceClass ExcelSaveDiagnosticsNamespace OfficeIMO.ExcelDescribes which package writer was used by the most recent save operation.InheritanceObjectExcelSaveDiagnosticsFilter membersAll (3) Properties (3)Show inherited Expand all Collapse all ResetPropertiesWriter #The package writer used by the save operation.UsedFastPackageWriter #True when the save used a fast package path instead of full package finalization.FastPackageSkipReason #Reason the fast package writer was skipped, when the save fell back to full package finalization.