It's important to note that while the DoD is the largest user of RDT&E funds, other government agencies, such as the Department of Energy, NASA, and the Department of Homeland Security, also have RDT&E appropriations.
Here's why RDT&E is considered an appropriation:
* Appropriations are the legal authorization for the government to spend money. Congress allocates funds to specific programs and activities through appropriations bills.
* RDT&E is a specific program that focuses on developing new technologies, systems, and capabilities for the military.
* The DoD's RDT&E appropriation is a major part of its overall budget, supporting research and development efforts across a wide range of military technologies.
Therefore, RDT&E is an appropriation within the DoD budget and other agencies' budgets, enabling them to invest in research and development activities.