Operations like linking and object embedding need applications to work together in a coordinated fashion. However, there is no way that Windows can be set up, in advance, to accommodate all the applications and dynamic link libraries that can be installed. Even within an application, the user has the ability to select various components to install.
As part of the installation process, Windows requires that applications supporting DDE/OLE features register their support by storing information in several different locations. The most important of these to cypress enable is the registration database.
WIN.INI
The win.ini file contains a special section called [embedding] that contains information about each of three applications that operate as object servers.
The Registration Database.
Starting with Windows 3.1, Each Windows system maintains a registration database file that records details about the DDE and OLE functions supported by the installed applications. The database is stored in file called REG.DAT in the \ WINDOWS directory.