I have a suggestion of the answer. I suppose someone could get a confirmation lose but it would be from some pretty cagey folks who have made obscene amounts of money. Lexis/Nexis, in an effort to deal with the complete lack of optimized solutions for dealing with massive search and inddexing problems... They took several IBM mainframes beginning with the old 370 architecture days and put them together in what today would be a cluster. At the time it was all big iron, and there was no O/S per se, it was all customized IBM assembler. Today the core iron is still all IBM, but the outer edges are all client/server worstations and servers. It is apparently configured in a massively parallel configuration around the IBM mainframe core. I would propose that the core IBM mainframe code has changed only incrementally over time, and hence is probably the some of the oldest code in the industry still running. I guess logic would prevent one from assuming that no changes have been made as the hardware has been upgraded, but that core code has got to be ancient. mdw ;-)