External entities in the context of a DFD maybe which of the following?

Which of the following is a data flow diagramming rule?

For the Observer Design Pattern, which one is false:

PERT stands for:

A Data Dictionary:

CASE stands for:

Transaction processing (tp) systems _____.

Product-oriented firms manufacture _____.

An example of an attribute of an object might be _______.

The type of event that occurs outside of the system is called a(n) _______.

To avoid problems, preventive maintenance _____.