Be familiar with subroutines and their uses. Know that a subroutine is a named ‘out of line’ block of code that may be executed (called) by simply writing its name in a program statement. Be able to describe the use of parameters to pass data within programs. Be able to use subroutines with interfaces Be able to use subroutines that return values to the calling routine. Know that subroutines may declare their own variables, called local variables.