Posted Sep 26, 2013 1:26 UTC (Thu) by davecb (subscriber, #1574)
Parent article: A perf ABI fix
Literal version numbers are what most people use, but they need not be that simple-minded. The pre-IP ARPANET also used a one-bit version number, according to an old colleague.
This is also an elegant solution to the "how do I introduce versioning" problem, exactly as was faced by the RCS developers when they first had to introduce an incompatible change. Something that's at least physically there (albeit not always "logically" there) gets used as the indicator, and everything thereafter can have as wide a version number as it needs.
If this structure only changes every 10-20 years, a one bit width will probably do for all time (;-))