The release schedule should include dates for the following freezes.
The particular module is completely frozen for commits without prior approval from the person managing that release.
To request a code freeze break, file a bug with attached patch and mark it blocker, then email or contact the release manager on IRC to ensure they're aware of the bug.
Modules may only depend on released (or shortly to be released) versions of other GStreamer modules. For example, the dependency of Good Plugins may not be changed to require a CVS install of Core.
Dependency freeze ensures that a module will stay releasable until it is time for it to be released.