A related interesting question is what happens when a set of packages cause a circular order dependancy. My immediate reaction was 'we say tough' but on reflection it isnt a viable answer
What may be a valid ordering on Red Hat and Debian might suddenely not turn out to be on Caldera. In addition installing any future package requires recomputing the entire dependancy graph and may cause loops. Worse removing a package might introduce a loop if it has to do things in its cleanup to remove hooks
