Some people have pointed out the fact we currently already have a categorization system which is in use. This system doesn't exactly work well for end user/third party filtering. (Note I haven't played with the API in regards to this) Currently our system shows the contents of what is in it which is fine for when your looking for something in it, but to filter something you need to be easily get the file(name/s) of the contents in it en-mass for the content so they can be added to the relevant systems.
For example, Showing real content, There is a difference in adding any of the three to a filter list: * http://en.wikipedia.org/wiki/Category:Cats (The Category) * http://en.wikipedia.org/wiki/File:ParliamentaryCats.jpg (The Description Page) * http://upload.wikimedia.org/wikipedia/en/e/ec/ParliamentaryCats.jpg (The Actual File)
The last one (and the subsequent thumb files) is what we need to be easily identifiable [The Filenames and Full Paths] so they can be dealt with as required by the filters, For example a list that is automatically produced per category so they can be imported (Is there any standards for importable lists into filters??).
-Peachey