+0     WORD  Turn number
   +2   7 BYTEs junk.
   +9  10 BYTEs Signature 2 (see GENx.DAT)
  +19  83 BYTEs junk. This and the previous "junk" block are perturbed at
                every unpack and seem to serve no purpose (they are not
                used again).
 +102 500 RECORDs of 8 bytes each: Mine fields
                 +0     WORD    X
                 +2     WORD    Y
                 +4     WORD    Radius
                 +6     WORD    Owner/Type
+4102  50 RECORDs of 12 bytes each: Ion storms
                 +0     WORD    X
                 +2     WORD    Y
                 +4     WORD    Radius
                 +6     WORD    Voltage in MeV
                 +8     WORD    Warp
                +10     WORD    Heading in degrees
+4702  50 RECORDs of 4 bytes each: Explosions
                 +0     WORD    X (0 = non-existent)
                 +2     WORD    Y
+4902 100 RECORDs of 78 bytes each: Ufos, see UFO.HST
+12702  4 BYTEs Signature "1211", if all visual contacts fit into the normal
                TARGETx.DAT file, "1120" otherwise.
 +?  16 BYTEs   ? (unused)
--- Additional Visual Contacts ---
 +?     DWORD   Number of contacts
 +?   n RECORDs of 34 bytes each
                 +0     WORD    Id Number
                 +2     WORD    Owner
                 +4     WORD    Warp
                 +6     WORD    X location
                 +8     WORD    Y location
                +10     WORD    Type of hull
                +12     WORD    Heading in degrees, 0=North, 90=East,
                                180=South, 270=West, -1=unknown
                +14  20 BYTEs   Ship name, encrypted
                                  FOR i:=1 TO 20 DO
                                    Encrypted[i] := Original[i] XOR (155-i)
                Note that, except for the encrypted ship name, this is
                exactly a TARGETx.DAT record.
--- always ---
 +?  10 BYTEs   Signature 2 (see GENx.DAT)

For a more detailed description of the data formats, see the RST file description. This one contains a very similar data structure, except that the RST contains the race names, KOREx.DAT doesn't.

This is a testing version.
It may be incomplete, and have more bugs (or features) than the public live version at planetscentral.com.