Some version number systems aspire to merely label changes in an interface, but there is much in the human experience that lies outside of this. Sometimes a version is just a number, but sometimes what we really want is a poem.

Semver has a spec, but Sentimental Versioning has not a spec, but a guide; just some whimsical suggestions. If you use sentimental versioning you should not copy another sentimental versioning system. You should do something creative and original. You may explain the system you create, if the beauty is enhanced by understanding it. You may just improvise new numbers from your mood on that day. The only important thing, is that the version number must be meaningful to you, the author.

Interpreting the previous paragraph according to the specific meanings defined in RFC2119 for “should”, “should not”, “may”, and “must” is entirely optional.

Following are some projects that use sentimental versioning. Draw inspiration from the way their version numbers express intangible aspects of the project, and are a work of art on their own.

node.js is like a rebellious teenager. It skips class and plays in a punk rock band - yet still gets straight A’s. ts versioning system expresses its dual nature beautifully. Version numbers alternate between even and odd, and between stable and unstable. In unstable versions node makes its own rules and sticks it to the man. In stable versions node wears a long sleeve shirt over its tattoos and works at fortune 500 companies (fighting the system from the inside?). Some critics say that node is part of the establishment now, citing that it’s been a very long time since its last album was released, version 0.12 having been in the works for over a year. While this accusation may carry some weight, you cannot put a time frame on creativity, and you must admit that node’s use of sentimental versioning is a beautiful expression of its own internal conflicts.

Jeremy calls his versioning system romantic (which is very sentimental of him) It looks like semver (major.minor.patch), but with a personal meaning. For him, a patch is a change you probably won’t notice, and a minor change is when you change it a little bit. A major change is when you make a major release (notice the circular definition!). A major change can be anything or nothing. He says every change should be backwards compatible. But what does “backwards compatible” mean to Jeremy? That is up to you to decide. Jeremy’s use of sentimental versioning expresses how backbone is his masterpiece, and he, its master.

In his seminal text layout system, TeX, and his equally brilliant typeface design system, METAFONT, Donald uses a versioning number system that asymptotically approaches perfection. The version numbers of TeX approach π (the current version is 3.14159265) and the version numbers of METAFONT approach e. It has been prophesied that the last change not be made until after the day Donald ascends to heaven on a shining cloud. At that point, Donald will make one last ssh connection down from heaven to his server at Stanford University and set the version number unto π exactly. At that point all remaining bugs will be declared features, and the output from TeX will remain the same for all eternity.

What ever happens, not everyone will understand your intentions, possibly your genius will not be recognized within your lifetime. But we did not choose the life of the artist for fame and certainly not for fortune - But rather, a dedication to aesthetic beauty and self expression.

In this spirit, go forth, and create beautiful versions!.