6.4.1 Arguments to Functions and Subroutines

The parameters to a function or a subroutine are the variables, local to the routine, that the user can specify values for and that are referred to inside the function or subroutine. The arguments are the values that the user specifies for these parameters.

The arguments of a routine can be specified in various ways. In addition, you may leave some or all arguments to a subroutine or function unspecified.