A data memory for storing elements, which data memory stores the data of the elements and at least a chained list which contains, for each stored element, at least its element address, its element number and a pointer to the address of the stored element having the next-higher element number. There are also provided an element status table, in which the element numbers of the elements present in the data memory are taken up, and also an address reference table which contains the element addresses for all element numbers.