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*If you really want the details: when you modify cost object allocations, you can add and remove multiple allocations at once. So if you had allocations for Fab processing to cost objects A and B and you removed both of those and added cost objects C and D, MUMMS would not know what to do with the existing activities that had been charged to cost objects A and B (whether they should be applied to cost object C or D or some combination of the two). There is, however, a separate function in MUMMS that will allow a one-to-one replacement of a cost object retroactive to the beginning of the current billing period (documentation forthcoming)see the Replacing a Cost Object page for details.