For example, an option string x recognizes an option -x, and an option string x: recognizes an option and argument -x argument.
The options parameter may contain the following elements: individual characters, and characters followed by a colon to indicate an option argument is to follow. For example, an option string x recognizes an option -x, and an option string x: recognizes an option and argument -x argument. It does not matter if an argument has leading white space.