doc = Document.new(source)
raise InvalidErdFile unless doc.elements.to_a.length == 1 and doc.elements[1].name.downcase == 'drawing'
self.mark = doc.elements['Drawing'].attributes["mark"].to_f
doc = Document.new(source)
raise InvalidErdFile unless doc.elements.to_a.length == 1 and doc.elements[1].name.downcase == 'drawing'
self.mark = doc.elements['Drawing'].attributes["mark"].to_f