Microsoft Excel Template (.xlt) are template files created with Microsoft Excel which is a spreadsheet application which comes as part of Microsoft Office suite. Microsoft Office 97-2003 supported creating new XLT files as well as opening these.
Learn more about this file format here
GroupDocs.Viewer (in GroupDocs.Viewer.dll) Version: 20.6
public static readonly FileType XLT
Public Shared ReadOnly XLT As FileType
static initonly FileType^ XLT