For the complete specs on gedcom (over 100 pages of technical stuff)
ask for the gedcom specifications and send $5 to:
   
    Family Search Support Unit
    Family History Dept 4WW
    50 East North Temple
    Salt Lake City, UT 84150
  
The best way to get an idea about what a gedcom file is, is to create
a small one (or download a small one) and look at it.
  
