gui, lol.

Property Name="UnifiedAreaRect" Value="{{left_relative,left_offset},{top_relative,top_offset},{right_relative,right_offset},{bottom_relative,bottom_offset}}" />

the awesomenes of CEGUIs layout syntax > all.
ok, the only other layout syntax i know is css and it sucks so much.

XML can be a useful tool, but it's no panacea to data storage and translation problems.

There are too many people out there who want to jump onto the latest technologies regardless of their actual utility to the problem at hand.