Request for method to work out what is using space in file


I am one of the software convenors for the ND280 collaboration. We are currently trying reduce the size of our data files, which are in ROOT format. It has proved rather awkward to find out what is taking up the space in our files. Could I put in a feature request for a method to find out where space is being used in a file. The only mention I have seen in this forum refers to using TTree->Print(), however we are not using TTrees so that does not help us. A more generic solution would be appreciated.

                                                        Alex Finch