2.2.2 A product code in an answer file. Let’s say you have a WIM image of Windows 7 Enterprise and a Multiple Activation Key (MAK). How do you assign the MAK on all target computers? It would be very uncool to go around and manually enter the MAK on every computer. You can specify the MAK by using an answer file. The answer file will be used for the deployment.
The details of how answer files work are a lengthy and distinct story that may be told at another time. An answer file is an optional XML file that contains the settings that Windows 7 Setup applies during installation. The setup process is divided into phases, which are called configuration passes. An answer file contains sections that correspond with the passes. A setting in an answer file is applied during a configuration pass. It is located in the section where it is found. Sections should not be placed at random. Each supported setting must be placed in the correct place for an answer file to be valid.
There are two locations–actually they are XML elements -where a product key can actually be specified in an answer file:
Microsoft-Windows-Shell-Setup\ProductKey
Microsoft-Windows-Setup\UserData\ProductKey\Key
The first element should go in the Specialize section. The MAK in that element will be used to activate each target computer’s installation. Windows 7 will attempt to activate the installation within 72 hours after completion. If the computer’s end user activates the installation manually, Windows 7 will automatically activate the installation.
If the problem is solved, what’s the purpose of the second element? The WindowsPE section can specify the second element. Its purpose is to identify which image is to be installed. Multiple installation images can be stored in a WIM file for different editions of Windows 7. Retail product keys can only activate a specific edition. For example, a retail key for Windows 7 Home Premium will not activate Windows 7 Professional. You can provide a key for a specific edition to instruct Setup to install that edition. The key in the WindowsPE section cannot be used to activate the installation. MAKs, unlike retail product keys are much more selective when it comes editions. However, the same MAK can be used for any VL edition Windows 7. There are many ways to identify an installation picture. You can use the following element to identify the correct image:
Microsoft-Windows-Setup\ImageInstall\OSImage\InstallFrom\MetaData
This element can only be specified in the WindowsPE section, because Setup selects an Image to install during the WindowsPE configuration pass.

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