The term "open source" as referring to sofware was suggested in 1997 but I could find references to OSINT from at least 1991-1995[0], so I'd say "Open Source In

The term "open source" as referring to sofware was suggested in 1997 but I could find references to OSINT from at least 1991-1995[0], so I'd say "Open Source Intelligence" should get precedence. [0] https://apps.dtic.mil/sti/tr/pdf/ADB194025.pdf https://apps.dtic.mil/sti/tr/pdf/ADB194025.pdf