FREMO is an abbreviation for "FReundeskreis Europäischer Modellbahn", roughly translated into Friendship Association of European model railroad builders. As the name implies, this is originally a German association, founded in 1981, and later expanding to encompass many countries and nearly two thousand members.
The idea behind FREMO is to get together and operate on large model railroad layouts, and these layouts comprises many smaller modules, which the members themselves build and own. To achieve this, there has been adopted a common modular standard, and this standard (or norm, if you like) defines, among other things, how the modular interface should be, how electrical connections between the modules should be executed, and what kind of train control system to be used, allowing different modules to fit together without problems.
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