XVT-Draw is a vector graphics drawing program. There were versions for Macintosh, Windows 2.x/3.x, and maybe other platforms. It was developed by Marc J. Rochkind and Advanced Programming Institute Ltd.
XVT-Draw is an early example of an application that uses the XVT (Extensible Virtual Toolkit) portability toolkit.
The Windows version has a native .vtd file format. The documentation says that the Macintosh format is different and incompatible.
VTD files start with bytes
0x31 0xd4 (decimal 54321).