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Source: https://writers.stackexchange.com/a/46533
License name: CC BY-SA 3.0
License URL: https://creativecommons.org/licenses/by-sa/3.0/

Source: https://writers.stackexchange.com/a/46533
License name: CC BY-SA 3.0
License URL: https://creativecommons.org/licenses/by-sa/3.0/

# Software numbering

There are lots of schemes in use, and sometimes software vendors even switched between schemes.

The most important feature of numbered schemes (as opposed to pure naming schemes like "Windows ME, XP, Vista") is that the version numbers always increase, that is, later versions get greater version numbers (what "greater version number" means however depends on the chosen numbering scheme).

For numbered versions, there are four main concepts:

- The "integer" concept: The version is just numbered 1, 2, 3, ...

- The "floating point" concept: This is a straightforward extension to the integer version, where the version number is treated as a floating point value.

- The "list of integers" concept: This treats the version number as a lexicographically ordered list of integers. The first integer is known as major version number, the second as minor version number. A third number, if it exists, usually denotes pure bug fix releases. In rare cases there may even be a fourth number (for example with gcc, there were versions 2.7.2.1 to 2.7.2.3).

- Date based concepts: The version number indicated the time of release, like Windows 95, 98 and 2000, as well as Ubuntu's year.month numbering scheme.

Note that the used concept affects the ordering of the releases: Following the floating point concept, Windows 3.11 was released earlier than Windows 3.2, while due to using the integer list concept, Linux 3.2 was released before Linux 3.11 (with Linux 3.3 to 3.10 in between).

# Spacecraft numbering

From what I gather from browsing [this site,](http://claudelafleur.qc.ca/Spacecrafts-index.html) the most common scheme for spacecrafts seems to be just the craft's "family name" followed by an increasing number. Sometimes there are letters instead of numbers (like CRO A, CRO B, CRO C), or combinations of both (like Astra 1-B).

Original score: 3