Object, database, and distributed object expectations have since been glued to XML in a series of specs that claim to be XML or use XML in ways that obscure what's actually happening when you use markup. The kind of data that is captured within a XML file is usually one of these (very) different types.
A related approach, that doesn't always rely on a xml format is the one of templating systems. XML helps separate data from the resource and the application for greater interchange. Templating systems help separate elements of the user interface from the logic of the application (the code):