Area 0

The first area created in a schematic is area 0.  This area is created first, but it is checked last when accidents are being added to the diagram.  This special area may not be deleted because it is designed as a 'catch-all' for any accidents that don't fit in the other areas.  Except under unusual circumstances, this area should always contain the condition TRUE.  This assures it of catching all accidents that aren't placed elsewhere on the diagram.