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Applications that wish to participate in DDE must be registered in the Windows registry database. In this database, the operating system stores, in the binary format, the information it requires to organize the conversations. Generally, this registration is done automatically when you install a product, but if you encounter problems, you can view/edit the application's DDE properties.
To do this, click on the Windows '95 Start button and select Run and type in REGEDIT. This runs REGEDIT.EXE, bringing up the Registry Editor window.
Unless you understand exactly how the registry works, you can cause your system to lose functionality. Let's see what entries we have for the DDEExec parameter, for the MS-Word program. Double-click on HKEY_CLASSES_ROOT/Word.Document6/Protocol/Shell/Open/DDEExec. You will see the value of this variable in the right hand side window, as shown in the following picture. The value there says, open the specified file:
The 'Application' and 'Topic' options are used to refer to the application, you want to communicate with. Let's take a look at each of these entries in detail, while also introducing Item, a subdivision of topic.
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