Three of the most popular local area network systems are Ethernet, IBM Token Ring, and Wireless Ethernet.?

Define this abstract data type using an algebraic specification.

An abstract data type representing a stack has the following operations associated with it: New: Bring a stack into existence Push: Add an element to the top of the stack Top: Evaluate the element on top of the stack Retract: Remove the top element from the stack and return the modified stack Empty: True if there are no elements on the stack

A typical enterprise consists of a wide variety of departments, centers, and divisions -- collectively known as ______ units.

Fill in the blank(s) with the appropriate word(s).