The practice of increasing the version number of a given piece of
software in other than a regular, steady pattern. Sometimes this
is to keep up with similarly-featured competitors whose numbering
scheme is at a higher level; the makers of Floobilnznorker 3.4 don't
want to appear to be playing second fiddle to ProZnorker 4.0 -- even if
their numbering schemes are based on entirely different criteria, or if one
product came much later than the other, etc. The most extreme example
would be a software product which enters the market with a large number
other than 1.0 after its name. Famously (at least to users of Free
software
, the version numbering of Slackware Linux moved after a long
steady progression to 7.0, skipping the major versions numbers 5.0 and
6.0, about which Slackware lead Patrick Volkerding said (in comments on Slashdot: "I think it's
clear that some other distributions inflated their version numbers for
marketing purposes, and I've had to field (way too many times) the
question "why isn't yours 6.x" or worse "when will you upgrade to Linux
6.0?" This illustrates the merry-go-round of marketing --> public
perception
--> reality, and the challenges that those who pick the
numbers have to face. The Linux kernel, in contrast to many Linux distributions (several of which will soon be flirting with double digits) has an enviably restrained
version-numbering system, so far.