ExcelTemplate.Open

Overload	Description
Open(ExcelApplication, Workbook)	Passes a spreadsheet from ExcelApplication to ExcelTemplate.
Open(String)	Opens an ExcelWriter template spreadsheet. A template is a file created in Microsoft Excel that contains data markers where data source values will be inserted.
Open(System.IO.Stream)	Opens an ExcelWriter template from a `System.IO.Stream`. An ExcelWriter template is a file created in Microsoft Excel that contains data markers where data source values will be inserted.

Overload	Description
Open(Microsoft.SharePoint.SPDocumentLibrary, String)	Opens a spreadsheet from a SharePoint Document Library.
Open(Microsoft.SharePoint.SPListItem, String)	Opens a spreadsheet from a SharePoint List Item.