Editing Software versioning (section)

===TeX===
[[TeX]] has an [[idiosyncratic]] version numbering system, an unusual feature invented by its developer [[Donald Knuth]]. Since version 3.1, updates have been indicated by adding an extra digit at the end, so that the version number [[asymptotically]] approaches the number [[pi|{{pi}}]], so 3.14 effectively means 3.2 in semantic versioning. (This is a form of [[Unary numeral system|unary numbering]]; the version number is the number of digits.) Since 2021, the version number has been 3.141592653 (3.9). This is a reflection of TeX being very stable, and only minor updates are anticipated. TeX developer Donald Knuth has stated that the ''"absolutely final change (to be made after [his] death)"'' will be to change the version number to {{pi}}, at which point all remaining bugs will become permanent features.<ref name="tb30knut">{{cite journal |last1=Knuth |first1=Donald E. |date=December 1990 |title=The Future of TeX and Metafont |url=https://tug.org/TUGboat/tb11-4/tb30knut.pdf |journal=TUGboat |volume=11 |issue=4 |pages=489 |access-date=7 September 2023}}</ref>

In a similar way, the version number of [[Metafont]] asymptotically approaches [[E (mathematical constant)|Euler's number, {{mvar|e}}]].<ref name="tb30knut" /> As of February 2021, the version number is 2.71828182 (2.8). Metafont was also devised by Donald Knuth as a companion to his TeX typesetting system.