.XLTHTML File Extension
File TypeMicrosoft Excel HTML Spreadsheet Template
What is an XLTHTML file?
HTML version of a .XLT spreadsheet template created with Microsoft Excel, a spreadsheet application; contains HTML that renders the template using similar formatting as the original XLT file; used for viewing published spreadsheet information in a Web browser.
XLTHTML files were not popular and are no longer supported by Microsoft Excel. To publish a spreadsheet template for a Web browser, save the template using the .MHTML extension from the in Excel 2010.