As every 6-year-old learns that there is real and there is make-believe. The massive post office deficit that is driving management to commit institutional suicide by ending six-day delivery, closing half of the nation's 30,000 or so post offices and half its 500 mail-processing centers, and laying off more than 200,000 workers, is make-believe. Here's why: In 1969, the federal government changed the way it did accounting. It began to use what was and is called a unified budget that includes trust funds such as social security previously considered off-budget because they were self-sustaining through dedicated revenue. At that time the Post Office was, as it had been since 1792, a department of the federal government like the Department of Energy or the Department of Agriculture. While generating most of its revenue from postage it also received significant Congressional appropriations. In 1970 Congress transformed the Post Office into the U.S.