NATO Accessory Rail

The NATO Accessory Rail (or NAR), defined by the new modernization agreement Standardization Agreement 4694, is a new rail interface system standard for mounting accessory equipments such as telescopic sights, tactical lights, laser aiming modules, night vision devices, reflex sights, foregrips, bipods and bayonets to small arms such as rifles and pistols.
STANAG 4694, was approved by the NATO Army Armaments Group (NAAG), Land Capability Group 1 Dismounted Soldier (LCG1-DS) on 8 May 2009. It will be forwarded to the NATO Standardization Agency and then onto individual NATO nations, which will test the NATO Accessory Rail system for final ratification.
The NATO Accessory Rail is backwards-compatible with the STANAG 2324/MIL-STD 1913 Picatinny rail, which dates back to 3 February 1995, and was designed in conjunction with weapon specialists like Aimpoint, Beretta, Colt Firearms, FN Herstal and Heckler & Koch. The Heckler & Koch G28 designated marksman rifle features NATO Accessory Rails.
Technical specifications.
According to the NATO Army Armaments Group the differences between the MIL-STD 1913 Picatinny rail and the STANAG 4694 are:
Another notable change is the recommendation that while in the Picatinny rail system the V-angles are used for the alignment and reference of the accessory, NATO recommends using the top surface instead. Initial NATO tests had shown that the Picatinny rail system did not provide good repeatability. Using the top surface as a reference and alignment of the grabbers provided excellent repeatability.
Video cameras.
NATO rail design is also used for small video camera setups. Videos shot with DSLR or Mirrorless cameras use a variety of mounting systems for attaching microphones, monitors, lighting, and other accessories. A NATO-compatible rail is one of these systems. Although it is advertised to meet the same specifications, there is some discussion that some of the rails and accessories are not compatible with one another.
Further plans.
Further plans are underway to develop a NATO standard to provide electrical power to rail mounted accessories in the future. Currently, Wilcox Industries, in cooperation with Surefire, is working on the creation of a railed forend for an AR-15 that will power battery-reliant accessories such as tactical lights and laser sights. Accessories are intended to be powered by one central battery pack or via their proprietary vertical grip, the Universal Control Grip.