1. A method operable in a space-incremental garbage collector for processing remembered sets, each remembered set associated with a heap memory region, wherein the garbage collector operates on a collection set having at least one region therein, the method comprising: (a) sequestering remembered sets associated with regions in the collection set; (b) if a change is made to a reference location containing a reference that refers to an object in a region that is not in the collection set, updating the remembered set associated with that region; (c) if a change is made to a reference location containing a reference that refers to an object in a region that is in the collection set, recording the reference location on at least one reference location list; and (d) scanning reference locations in remembered sets associated with regions in the collection set and recording on at least one reference location list those reference locations containing references that still refer to objects in regions that are in the collection set.