GNU EMACS VERSIONING                                   -*- org -*-

Ref: https://lists.gnu.org/r/emacs-devel/2014-09/msg00872.html

Emacs version numbers have the form

  major.minor[.devel].build

"build" increments each time Emacs is built in the same location
(without cleaning) and isn't really part of the version.

Bugfix-only or otherwise minor releases increase "minor" by 1.
Feature releases increase "major" by 1, and reset "minor" to 1.

Unreleased (development) versions have an extra "devel" component.
This is a fairly meaningless number that may be unchanged for a long time.
It is normally 50, then 60 when the release branch is cut.

After we cut the release branch, we’ll make pretest and release
candidate (RC) releases.  For pretest releases, the "devel" component
changes to 90, 91, ...  When the first RC release is made, this
component is removed.  Normally, there is one RC release, unless an
unexpected last-minute problem occurs.

The development version for a new major release has "minor" = 0.
The development version for a new minor release has "minor" = that of
the previous release.
