He documented this plan already in 1990: > At the time of my death, it is my intention that the then-current versions of TeX and METAFONT be forever left uncha

He documented this plan already in 1990: > At the time of my death, it is my intention that the then-current versions of TeX and METAFONT be forever left unchanged, except that the final version numbers to be reported in the “banner” lines of the programs should become > TeX, Version $\pi$ > and > METAFONT, Version $e$ > respectively. From that moment on, all “bugs” will be permanent “features.” (See http://www.ntg.nl/maps/05/34.pdf http://www.ntg.nl/maps/05/34.pdf)