Behind the Scenes

Web developers can associate their Web sites with their Windows 8 apps through simple markup on the site by including the following meta tags in the element of their Web pages. Both tags are required for Metro style Internet Explorer to provide the site icon button.

<meta name="msApplication-ID" content="microsoft.build.App" />

<meta name="msApplication-PackageFamilyName" content="microsoft.build_8wekyb3d8bbwe" />

When these tags are present, Metro style IE uses them to identify if the app is already installed on the PC and, if not, to provide a direct link to the app description page in the Windows Store. The desktop version of IE10 on Windows 8 does not provide this linkage.
These two required tags are among the five possible tags available for controlling site/store/app interaction. Below is a complete table of the tags.

name	content
msApplication-ID	Required. Package-relative app-ID from Application Manifest. Used to link your site to your app.
msApplication-PackageFamilyName	Required. Package Family Name of the app created by Visual Studio when the app is published. Used to link your site to the store.
msApplication-Arguments	Optional. Argument string passed to your app. By default, IE passes the URL of the Web page but you can use this to pass a context-relevant string.
msApplication-MinVersion	Optional. Enforces a required minimum version for the installed app. If the user tries to switch from the Web page to an outdated app, he or she is first taken to the Store to update the app.
msApplication-OptOut	Optional. Allows pages to opt-out of all or parts of this functionality: “install” prevents offering the user to get the app when they do not have it installed “switch” prevents offering the user to switch to an already installed app “both” prevents both offers