Status of XEmacs 21.x

Hi Folks! I am new to this list and a little bit confused about the different stati of the different XEmacs's. For example, the 21.0.67 version of XEmacs appears not in a beta-folder, but after compiling the logo show me a warning about the beta status of the editor. There is also one higher version developped in parallel... And still there is the Emerald version (20.4), which isn't beta (?). which I currently use. Any help to avoid more confusion ;-) is very appreciated. KEEP HACKING! Meino