**NATO Off-The-Shelf (NOTS) or niche off-the-shelf, depending on the context) product is developed by NC3A (for NATO Consultation, Command, and Control) to meet specific requirements for NATO. In the more general context, niche off-the-shelf refers to vendor-developed software that is for a specialized and narrow market segment, in comparison to the broad market for Commercial Off-The-Shelf (COTS) products.
Source: NATO Off-The-Shelf (NOTS)