Supported files
Any file which contains LWM or VTP information should load and display correctly. The list of common types for FS2004 is:
AB : Airports
AP : No terrain data, unlikely to load
BR : Bridges
FL : Flattens (usually matching the airports)
HL : Shorelines
HP : LWM (Land/water mask)
PK : Public Parks (thanks, H.)
RD : Roads
RR : Railways
ST : Streams
UT : Utilities (power pylons etc.)