500 records of 12 bytes each
 +0     WORD    X
 +2     WORD    Y
 +4     WORD    Owner
 +6     DWORD   Number of Mine Units. The radius of each mine field is the
                square root of this value.
                The maximum value here is 3000ⲽ9,000,000 (3000 is the
                maximum possible mine field radius that can be set in
                HCONFIG), resp. 25,000,000 (maximum set by the Host
                program).
+10     WORD    Type
                 0      Normal Mines
                 1      Web Mines

Unused minefields are identified by the radius and owner being zero. Non-Crystalline Web Mines are problematic. They can't be transmitted to Winplan (see KOREx.DAT), and Host does sometimes still assume that Web Mines always belong to the Crystals.

Minefields with Id greater than 500 are stored in EXTMINES.HST (PHost).