Visio Drawing Template (.vstx) are drawing template files created with Microsoft Visio 2013 and above. These VSTX files provide starting point for creating Visio drawings, saved as .VSDX files, with default layout and settings.
Learn more about this file format here
GroupDocs.Viewer (in GroupDocs.Viewer.dll) Version: 20.9
public static readonly FileType VSTX
Public Shared ReadOnly VSTX As FileType
static initonly FileType^ VSTX
static val VSTX: FileType