# File lib/FileSystemImage.rb, line 45
def compatability_score
  if @compatability_score.nil? then
    image_format_compatability_score=image_format.compatability_score(self)    
    if image_format_compatability_score>0 then #if we don't have a valid image_format, don't bother checking the file_system!
      file_system_compatability_score=file_system.compatability_score(self)
      @compatability_score=file_system_compatability_score*image_format_compatability_score
    else
      @compatability_score=0
    end
  end
  @compatability_score
end