Multiple layouts
The feature introduced in XFree86 4.3.0. It allows to concatenate one-group symbol descriptions into the complex, up to 4 groups (hard limit by XKB) layouts.
Currently this feature is supported by
* <a href="http://www.xfree.org/releases/rel430.html">XFree86 Release 4.3.0</a>
* <a href="http://www.xfree.org/releases/rel440.html">XFree86 Release 4.4.0</a>
* <a href="http://www.xfree.org/releases/rel450.html">XFree86 Release 4.5.0</a>
* <a href="http://xorg.freedesktop.org/wiki/ReleaseNotes670">X.Org Release 6.7.0</a>
More about this feature read here in PDF or here in OOo format.
-- Main.?SergeyUdaltsov - 10 Sep 2007