* ''NNN'' (New Nordic Norm, marketed by [[Rottefella]]), where a bar in the toe of the shoe is hooked into a catch in the binding. Also exists in the more rugged ''BC'' (Back Country) variant. Two small ridges run along the binding, corresponding with slits in the boot. There have been several versions of NNN, and the first NNN version is not compatible with current designs.
* ''NIS'' (Nordic Integrated System) is the latest incarnation of NNN known, unveiled by [[Skis Rossignol|Rossignol]], [[Madshus]], Rottefella, and [[Alpina Žiri|Alpina]] in January 2005;<ref>http://www.nordicskiracer.com/Equipment/2005/NIS/NIS.asp</ref> The new system offersfeatures integrated binding plate on the top of the ski to which the bindings connectattach, allowing easy installation of bindings and even adjusting them on-the-fly depending on weather and snow conditions. NIS bindings and boots are fully compatible with NNN boots and bindings, and NIS skis allow installation of SNSnon-NIS bindings. In 2007, [[Fischer]] abandoned SNS and entirely switched to NIS; at the same time, [[Atomic Skis|Atomic]] abandoned NNN and switched to SNS.
