... see also Radio positions and optical IDs II. ... Accurate position measurements and optical identifications for radio sources selected at 966 MHz University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfield, Cheshire SKI I 9DL, UK Accurate radio positions and optical identifications are presented for 538 radio sources selected from a survey at 966 MHz. ... The 3CR sample, selected at 178 MHz, has been identified by Longair (1965) and Wyndham (1965, 1966). ... ApJ 157,...