A merge module is a special kind of Windows Installer database that contains the components needed to install a seperate software bundle. A merge module cannot be installed alone, but must be merged into a standard Windows Installer installation during compile of the installation. Typically, a merge module or a collection of merge modules related by dependencies installs a software product or portion of a product at runtime. The purpose of merge modules is to let you add self-contained software modules to multiple installations. See Merge Modules in the Windows Installer SDK Help.
Use the Merge Modules page to add merge modules to an installation. By default, merge modules are not installed with Wise for Windows Installer. However, you can create merge modules or use the Download Redistributables wizard to obtain third-party merge modules and merge modules authored and tested by Wise Solutions.