The need for a classification of documenation artefacts

Today I had a very interesting discussion with my colleague Jarek concerning iDocIt!. During the discussion the question came up whether the interface is the right place for some of the documented characteristics of the operation, e.g. test cases formulated by the tester. I remember that I was confronted with this question in many discussions over the last months.

From my point of view there is a real need for a systematic of

• which places / artefacts exist in a project containing documentation?
• which kind of documentation contents exist?
• which content should be stored in which artefact?

Yet, we don't support such systematic with iDocIt!. I am very interested in the opinion of the you readers on this topic: did you see and use such systematic in your projects?