@gabber, concerning the use of the words "libraries" and "applications":
I am not really happy with my words, but still find them simpler and clearer than your suggestion "inputs" and "leaves". An input is a concrete input, I want to express "packages that appear essentially as inputs"; for instance when we remove them it is often because they are not an input to anything anymore, but have in fact become leaf packages. Likewise for "applications", that may or may not be leaves at some point in time; I want to express "packages that are typically installed into user profiles". And of course with dynamic languages such as Python the distinction sort of falls apart, but we already make them in our naming conventions, such as in "python-scipy" vs. "sage". I am open for better word suggestions that combine being (sort of) correct and snappy! Andreas
