During normal installation, the install program will prompt for various things such as install directory, license key, complete/custom install, etc. A silent install allows these items to be specified on the command-line or in a file so that the installation does not require any user input at the keyboard. This is useful when using automated install tools to push software to a new machine.
Enterprise 4.1 docs indicate it too has a unattended install capability but alas it is also for Unix only. I can only assume that newer versions still have this feature.
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