This container tag must is used to create a container which will encompass all of the other content that you wish to display. You will use it similar to an MTEntries block, and make use of other tags inside to display other content. You must add one of three attributes to the container to indicate how to retrieve your data: bloglines, opmllink or opmlpath.
The first option, bloglines, accepts a Bloglines user ID which can be used to pull your public subscription data from your Bloglines account. The second option, opmllink, can be used to specify a URL to an OPML file accessible somewhere online. The third and final option, opmlpath, can be used to provide a filesystem path to an OPML file.
You can specify all three options, but the bloglines attribute will take priority over opmllink, which will in turn take priority over opmlpath. So there is really no reason to do so! You will only make more work for yourself. Decide which format to use and specify that option only.