I am working on a prediction model in which I have several factor variables that have many levels. These factor variables have a nested structure, in the form of a Category, a Sub-Category, and a Sub-Sub-Category. For example suppose that I had one field that was the type of device a user browsed the website with (pc, tablet, phone), which then can be sub segmented into ((Apple, windows, linux), (kindle, iOS, android), (windows, iOS, android, RIM)), and then each of those could be subdivided into version numbers.
Is there a standard way of handling nested features like this in tree models. At an intuitive level, I don't think the tree should be splitting on one of the subgroupings until it has first split on one of the major groups (since a windows phone and a windows PC are quite different). Creating a single factor that describes the full tree path would have too many possible levels.