> This is useful in financial services where you have market data baked into a price you've offered to a client, where the underlying market data might have bee

> This is useful in financial services where you have market data baked into a price you've offered to a client, where the underlying market data might have been later corrected by a vendor. A long time ago, I worked on a such a system that provided service-based billing for an industry where rates were very fluid. Having this "at any point in time" view of key data was essential for many things.