Computer-readable medium storing a data structure for supporting persistant storage of a set of data, the data structure including: (a) at least an oldest version of the set of data in first memory area, the first memory area including at least one first tag for uniqueley indentifying the oldest version, and (b) at least a most recently updated version of the set of data in a second, distinct memory area, the second memory area including at least one second tag for uniquely identifying the most recently updated version. The invention also relates to a computer arrangement including a processor and such a computer-readable medium, as well as to a method of updating sets of data having such tagged-data structures.