According to this post OPML files are a handy way to exchange lists…usually I see OPML files as a collection of feeds from an RSS reader, but they are more than this, they can house a list of text/links made in an OPML outliner.
From the post:
“I can pull together a point of view with supporing exhibits, and publish the entire package to the web as a living, constantly updated knowledge environment
…use OPML to make a personalised online work environment for my daily research and writing”
So how do people view these OPML outlines (lists)?
Well they can have a URL and be published on the web and are viewed as a tree, and can be searched in an OPML search engine.
Instead of needing a blog or website for a daily updated presentation of new links to add to to your topic or bibliography list, you can use an outline list, an OPML list is much more suited for its simplicity as a focused topic packet list…you could make heaps of lists that you update and maintain…here is an OPML outline for the U.S. Constitution in OPML…and here is the OPML file.
These lists are published online, shareable, intergrated, can be modified, easily updated….and the items in the list aren’t just confined to text, they can point to webpages, and other file formats…all the benefits of the web 2.0 environment without really needing to know HTML.
So a tool like del.icio.us can hold a list of links and organise the links into tags, but they only go to one level, where as an OPML outline is different visually (similar to a directory tree), and can also hold content other than just web links, and it also very simple and versatile…it’s the precise tool needed for the job it needs to do.