We have seen that procedures are extremely useful for implementing modular program design techniques.
In this unit, we discuss another mechanism to modularize program code based on macros. Simply put, a macro is a sophisticated text subsitution mechanism.

The objectives of this unit are:

	To discuss macro definition and expansion
	To explain how blocks of statements can be repeated
	To describe conditional assembly directives
	To describe how to define a macro library
	To explore the performance tradeoffs associated with macros and procedures