heh
There is no kernel like that.
It's either -Release -Stable -Current.
Right now 4.6-Release is the current release.
From that they develop to -Current which is new code and not stable.
When it gets stable they move it to -Stable
After 3 or 4 months, they freeze -Stable which gets tested and tested and then eventually it comes -Release.
You use CVS ( concurrent versions system ) to download the sources and build world to update your entire operating system.
Thats is one of the major difference between unix and linux.
Linux is just a kernel while unix is a complete os.