The manifest file allows you to access your panorama offline. The online book, Dive Into HTML5, describes this quite well:
- At its simplest, an offline web application is a list of URLs — HTML, CSS, JavaScript, images, or any other kind of resource. The home page of the offline web application points to this list, called a manifest file, which is just a text file located elsewhere on the web server. A web browser that implements HTML5 offline applications will read the list of URLs from the manifest file, download the resources, cache them locally, and automatically keep the local copies up to date as they change. When the time comes that you try to access the web application without a network connection, your web browser will automatically switch over to the local copies instead.
Common Problem
One of the most common problems is the wrong mime type for the manifest file. You need to make sure that your webserver is serving the file with the type text/cache-manifest.
If you are using Apache as your web server you can add the following line to your .htaccess file to make sure that the correct mime type is used
AddType text/cache-manifest .manifest
To test the mime type you can use for example the command line tool curl with following line:
curl -I http://example.com/your.manifest