In the UK over the last decade or so a system of modules and faceplaces known as "Euro modules" seems to have taken off. Modules and faceplates are available from a wide-range of vendors. A regular "single" module is 25x50mm and there are also double-width 50x50 modules. The modules clip into a faceplate, with a "single gang" UK plate holding two modules and a "double gang" UK plate holding four modules.
Nearly all data outlets in the UK now use this format and an increasing range of other modules are becoming available. Initially it only seemed to be data/av/telecoms stuff, but mains stuff is now also available (though not common, the vast majority of mains stuff in the UK is still non-modular).
Is there an actual standard for these modules or is it just a de-facto thing? Are they used in other parts of Europe (the name and some pictures i've seen online suggests they are) and if-so what are they known as there)?