若有指定，就會為此站台建立含有指向該指定路徑之根虛擬目錄的根應用程式。若沒有指定，所建立的站台就沒有根應用程式，而且在建立根應用程式之前，都無法啟動。

If specified, will cause the root application containing a root virtual directory pointing to the specified path to be created for this site. If omitted, the site is created without a root application and will not be startable until one is created.