Software versioning is the process of assigning unique version names or numbers to unique states of computer software.

Since version 3, TeX has used an idiosyncratic version numbering system, where updates have been indicated by adding an extra digit, so that the version number asymptotically approaches π. The current version of TeX is 3.141592653; it was last updated in 2021.

Software versioning in which a version is an integer in degrees Kelvin.

Absolute zero is frozen — no further updates are possible. If your Kelvin versions don't track your actual progress, you run out of integers.

If tool B sits on platform A, either both A and B must be at absolute zero, or B must be warmer than A. Whenever the temperature of platform A declines, the temperature of tool B must also decline. Of course, if B itself is a platform on which some higher-level tool C depends, it must follow the same constraints recursively.