For pt.I see ibid., vol.3, p.9327 (1991). Oxygen contamination introduces hole-trapping centres into barium fluorohalides. In the preceding paper, an O^- centre was reported as the product of the reaction between out-of-plane Br₂^- V_K centres and oxide impurities. This paper describes an ENDOR study of this centre which identifies it as O_F^-, an oxygen ion substituted at a fluoride site. No evidence has been found for the presence of a neighbouring defect (anion vacancy or interstitial cation) remaining from its charge-compensating role for the proposed precursor O_F^2-.