The <%AppRoot%> tag is replaced with the relative URL root of the entire application without the trailing slash (/).
For example, the application root for http://myschool.brainhoney.com/Frame/default/Resource/89/test.vhtml would be a single slash (“/”).
If the application were hosted in a virtual directory, like http://www.myschool.com/brainhoney, this value would be “/brainhoney”.
Use this tag to reference resources or images from the root of the application.
For example, “<%AppRoot%>/Images/s.gif” would reference the application-supplied blank GIF file.