There are several types of arguments dealt with in this manual: arguments to command line options; non-option, positional arguments passed on the command line; and parameters passed to functions. When we refer to arguments passed to command line options, we will use the term argument on its own. When we refer to non-option, positional arguments passed on the command line, we will use the term positional argument. When we refer to the value of an environment variable, we will use the term value. When we refer to parameters passed to functions, we will use the term parameter.
When referring to a field in a C struct or union, we will
use the term field.
In examples, messages printed to standard output will be prefixed with “-|”, while messages printed to standard error will be prefixed with “error→”.