LilyPond Contributor's Guide: 11.1 Development phases

## 11.1 Development phases

There are 2 states of development on `master`:

1. Normal development: Any commits are fine.
2. Build-frozen: Do not require any additional or updated libraries or make non-trivial changes to the build process. Any such patch (or branch) may not be merged with master during this period.

   This should occur approximately 1 month before any alpha version of the next stable release, and ends when the next unstable branch begins.

After announcing a beta release, branch `stable/2.x`. There are 2 states of development for this branch:

1. Normal maintenance: The following patches MAY NOT be merged with this branch:
   - Any change to the input syntax. If a file compiled with a previous `2.x` (beta) version, then it must compile in the new version.

     Exception: any bugfix to a Critical issue.

   - New features with new syntax may be committed, although once committed that syntax cannot change during the remainder of the stable phase.
   - Any change to the build dependencies (including programming libraries, documentation process programs, or python modules used in the buildscripts). If a contributor could compile a previous lilypond `2.x`, then he must be able to compile the new version.
2. Release prep: Only translation updates and important bugfixes are allowed.

#### LilyPond — Contributor’s Guide