The National Codification Bureaus or NATO Codification Bureaux (NCB) are a NATO organization that oversees the management of the NATO Codification System (NCS). It is governed by NATO Allied Committee 135 (AC/135), with each member nation's National Codification Bureau controlling and issuing its own unique NATO Stock Numbers. NATO or European Union membership is not required to do so. Non-NATO (or "Partner") countries can be allowed to join if recommended, vetted, and approved by AC/135.