From the Document: "While the common use of the word 'procurement' implies the process of obtaining goods or services, uses of the word 'procurement' by national security experts and practitioners generally refers to a specific title within the annual National Defense Authorization Act (NDAA) and defense appropriations legislation. [...] Procurement funding authorized in a given fiscal year can usually be obligated over a period of three years. The most prominent exception is Navy Shipbuilding and Conversion funding, which is available for five years. The Department of Defense Appropriations Act, 2020 (Division A of P.L. 116-93) provided $133.9 billion in procurement funding for DOD in the regular, or 'base', budget, [...] in addition to $11.8 billion in procurement funding designated for Overseas Contingency Operations (OCO)."
CRS In Focus, IF10599
Congressional Research Service: https://crsreports.congress.gov/