What does ZIP 4 stand for?

ZIP 4 stands for "9 digit ZIP Code Plan"

How to abbreviate "9 digit ZIP Code Plan"?

"9 digit ZIP Code Plan" can be abbreviated as ZIP 4

What is the meaning of ZIP 4 abbreviation?

The meaning of ZIP 4 abbreviation is "9 digit ZIP Code Plan"

What does ZIP 4 mean?

ZIP 4 as abbreviation means "9 digit ZIP Code Plan"