Software version

Software versioning is the practice of assigning identifiers to distinct releases. This page records the scheme used on this wiki and the alternatives it was chosen over.

Scheme used here

Four sequences, major.minor.patch.build - the form used by the release logs on ASTAR, RTD1073, Netgem and Tiny6410, for example NTV350_Diag_1.0.3.4.

Field	Increment when
major	The interface changes in a way that breaks existing users.
minor	Features are added, but existing users are unaffected.
patch	Only defects are fixed.
build	A new build of otherwise identical source.

Any field that increments resets every field to its right.

Other schemes

Semantic versioning - three sequences with the same major/minor/patch

 rules made explicit and machine-checkable. See semver.org.

Date-based - 2015.04 or 20150401. Says when, not

 what changed; useful for rolling releases.

Year of release - marketing-facing, e.g. Windows 95. Carries no ordering

 information for a maintainer.

Degree of compatibility - some projects encode ABI compatibility in the

 major number so a linker can reason about it.

Practice

The version in the binary and the version in the tag must match. If they can

 disagree, they eventually will.

Never reuse a version number, even for a build that was never shipped.
An unreleased tree carries the next version with a suffix, not the last

 released version.

Reference