The program will report when you use arguments without a meaning to the program or when he found syntactical errors int the comand line. Common errors are the missing spaces between a parameter and its value. Another common error is a missing filename parameter -f before the filename. In this case the programm will not exit but wait for input until a CTRL-D is specified.
When using the +l and the -l parameter, be sure to have the list of sets closed by -1.
If warnings of an unknown option occur after execution of the program, but you are sure, that the options are alrigth, the reason might be an empty input file. If the input file is empty, the tool will not reach the test for some options.