uDb input

The uDB input is a binary file from an original version of Larry Hatch's U UFO Database, typically named U.RND.

File structure

The data file is a sequence of 112-bytes records.

A part from the first (#0) and last records which are system ones, the structure of a record is:

• 0 (0x00) : Sighting year (1 signed word)
• 2 (0x02) : Locale code (1 byte)
• 3 (0x03) : ? (4 higher bits)
• 3 (0x03) : Sighting month (4 lower bits to encode up to 12)
• 4 (0x04) : Sighting day (1 byte)
• 5 (0x05) : Sighting hour (1 byte) encoded as:
  • hour: value / 6
  • minutes: remainder/modulo value % 6 * 10 minutes
• 6 (0x06) : Year, Month, Day and Time (YMDT) accuracies (1 byte) encoded as 4 * 2 bits each encoding an accuracy level as:
  • 0 : DOES NOT APPLY/irrelevant (so not displayed).
  • 1 : Unknown/unspecified (displayed ?).
  • 2 : Approximative (displayed ~): within 1 or 2 Years or Months; within 3-4 Days, Hours.
  • 3 : Known: Exact year, month, day: Time within one hour.
• 7 (0x07) : Sighting duration in minutes (1 byte)
• 8 (0x08) : ?
• 9 : Longitude (15 lower bits of signed word / 1.11111)
• 11 : Latitude (15 lower bits of signed word / 1.11111)
• 13 (0x0D) : Elevation (1 signed word) in meters (-99 if N/A)
• 15 (0x0F) : Relative altitude (1 signed word) in meters (999 if N/A)
• 17 (0x11) : ?
• 18 (0x12) : Continent code (4 bits) + Country code (4 bits)
• 19 (0x13) : Area code (3 chars)
• 23 (0x17) : Location flags
• 24 (0x18) : Miscellaneous flags
• 25 (0x19) : Type of UFO / craft flags
• 26 (0x1A) : Aliens / monsters flags
• 27 (0x1B) : Apparent UFO / occupant activities flags
• 28 (0x1C) : Places visited and things affected flags
• 29 (0x1D) : Evidence and special effects flags
• 30 (0x1E) : Miscellaneous details flags
• 31 (0x6d) : Description (78 chars) as :-separated rows.
• 110 (0x6e) : Source code (1 byte) (see usources.txt file)
• 111 (0x6f) : Position in source (1 byte) but not complete
  • if page: No. of page
  • if vol/issue: lower bits are issue No.
• 112 (0x70) : Strangeness and credibility levels (1 byte), encoded as two hex chars (4 bits:4 bits)