TRL (Technology Readiness Levels)
TRL 1: Basic principles observed.
TRL 2: Technology concept formulated.
TRL 3: Experimental proof of concept.
TRL 4: Technology validated in lab.
TRL 5: Technology validated in relevant environment.
TRL 6: Prototype demonstrated in relevant environment.
TRL 7: System prototype demonstrated in operational environment.
TRL 8: System completed and qualified.
TRL 9: Actual system proven in operational environment.