Date and dash speed dating
speed may apply to human or nonhuman activity; it emphasizes the rate in time at which something travels or operates: the speed of an automobile; the speed of thought.
The most likely components to be original are the stem, handlebars, seatpost, and brakes.
The rear derailleur freewheel/cassette and chainwheels are probably the first to be changed on a bike.
Swaps can take place early in the life of a bike as the proud new owner upgrades to new or used components of higher quality.
Swaps also can be made as the bike falls out of favor, or is being sold, where the higher quality components are traded for lower quality ones that the owner had onhand.
Fueled by this first realization, and with the help of other bike folks, Larry and I have sorted out other codes (a project still ongoing).