The DDE acronym stands for the term Dynamic Data Exchange; an inter-process communication system built into the Windows operating systems prior to the release of Windows Vista™.

DDE enables two running applications to share the same data. For example, DDE makes it possible for VTS to report tag values to an Excel spreadsheet; whenever the tag value changes, the spreadsheet data changes accordingly.

DDE can also work to enable VTS to accept data from another application, such as a chart, word processing document or spreadsheet. To do so, VTS uses its DDE driver tag to facilitate communications between the external application and VTS.

The application that supplies the data is called the server, while the program that accepts the data is called the client. VTS can act as either a DDE client or a DDE server. The sections that follow provide instructions for configuring dynamic data exchange from an outside application to VTS, and from VTS to an outside application.