It is the -dem.dat terrain file that I am looking for information on.

Bruce

If you want to have a terrain file for your area, you should check out the "Map Generator" - http://mapgen.xcsoar.org/ I was able to enter min/max lat/lon and it generated a map in a matter of seconds. I found my lat/lon using Google Map "what's here". Note, I did have to convert the Google Maps lat/lon format to the XC Soar format, but there were plenty of converters on the web.

If you need a hand generating, just post your location and desired radius and some tech-savy person may just do it for you.