
Given the following passage

"Retail versions of Windows 8 are only able to install these apps through Windows Store—a namesake distribution platform which offers both apps, and listings for desktop programs certified for comparability with Windows 8. A method to sideload apps from outside Windows Store is available to devices running Windows 8 Enterprise and joined to a domain; Windows 8 Pro and Windows RT devices that are not part of a domain can also sideload apps, but only after special product keys are obtained through volume licensing.",

answer the following question. Note that the answer is present within the text.

Question: What additional feature is required in order to sideload an app with Enterprise? 

joined to a domain
