Experimental Drone Variant 4J, (UAS registration n/a)
Local copy of Experimental_Drone_Variant_4J_UAS_registration_N-A_04-26.pdf
Local copy of Glossary_of_abbreviations.pdf
https://www.gov.uk/aaib-reports/experimental-drone-variant-4j-uas-registration-n-slash-a
seen at 10:31, 9 April in Transparency and freedom of information releases.