Not sure that this will be in a single field? It is probably the difference between the PRTEAM.PRALLOCSUM and the sum of all the PRASSIGNMENT.PRESTSUM for the resource on the project. (That is a guess by the way - check it out on your database). (The values are in seconds I think, and of course this is the total per project, and not spread by time period, to do that you'd have to drop into analysing the slice information)