DDE (Dynamic Data Exchange) is an obsolete, though still used,
method of automating the exchange of data between two
applications. For example, a program written in VB6 or C would
open a DDE channel to Excel in order to insert values in to Excel
worksheet cells.
DDE has been largely replaced by OLE/ActiveX Automation.
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Cordially,
Chip Pearson
Microsoft MVP - Excel
Pearson Software Consulting, LLC
www.cpearson.com