public void setOptions(String optionString) throws MaltChainedException {
		this.optionString = optionString;
		format = PennWriterFormat.DEFAULT;

		String[] argv;
		try {
			argv = optionString.split("[_\\p{Blank}]");
		} catch (PatternSyntaxException e) {
			throw new DataFormatException("Could not split the bracket writer option '"+optionString+"'. ", e);
		}
		for (int i=0; i < argv.length-1; i++) {
			if(argv[i].charAt(0) != '-') {
				throw new DataFormatException("The argument flag should start with the following character '-', not with "+argv[i].charAt(0));
			}
			if(++i>=argv.length) {
				throw new DataFormatException("The last argument does not have any value. ");
			}
			switch(argv[i-1].charAt(1)) {
			case 'f': 
				if (argv[i].equals("p")) {
					format = PennWriterFormat.PRETTY;
				} else if (argv[i].equals("p")) {
					format = PennWriterFormat.DEFAULT;
				}
				break;
			default:
				throw new DataFormatException("Unknown bracket writer option: '"+argv[i-1]+"' with value '"+argv[i]+"'. ");		
			}
		}	
	}