Container multilingual is for the moment only an abstract notion to help understand better the various multilingual features of a cms.
"Container" is here meant as the opposite of Content multilingual. It refers specifically not to the translation of texts published within the website, but to the decisions of the webmaster as to the architecture of modules, structures...
For instance, you can have a menu translated (container), with pages linked by the menu remaining empty (content), or not translated.
The decision of the webmaster to allow German or not as one of the languages of the site is a Container multilingual decision. The activity of translating various pages of the same site into German is a Content business.
Generally it is to be assumed that few translators will be able to understand webmaster activities, and enticing them to site architecture decisions will only confuse them and prevent them to produce text. It is generally advisable to separate the two quite clearly in the user interface, so as to let the translators concentrate fully on Content.
There should even be a way, in case the webmaster requires a module or such objects translated by somebody else, to automatically produce a full text file and submit it to Content translators. A full text file or, even better, a form with read-only phrases and fields to fill. The example to follow is that of producers of translations in FrameMaker or Quark Xpress file, who only give translators rtf files, and thereafter have the translation inserted by FrameMaker or Quark Xpress professional designers.