code: public static void saveRelationsFile( FileDefinition relationsFile, boolean writeComments, String lineSeparator )
  	throws IOException {
  
  		if( relationsFile.getEditedFile() == null )
  			throw new IOException( "Save operation could not be performed. The model was not loaded from a local file." );
  
  		saveRelationsFileInto( relationsFile.getEditedFile(), relationsFile, writeComments, lineSeparator );
  	}
docs: Saves the model into the original file.
  @param relationsFile the relations file
  @param writeComments true to write comments
  @param lineSeparator the line separator (if null, the OS' one is used)
  @throws IOException if the file could not be saved