3+2 zip code (3+2 郵遞區號)

3+2 zip code
What does it stand for?

3+2 zip code
3= the first three digits are the adminstrative division (city, county, town, or  
     district)
2= the last two digits are the delivery section serial number (投遞區段序號),
     or the "designated delivery code" for addresses that recieve large amount of
     mail. (每日收受郵件較多之大宗戶之「投遞專用號碼」

For more informtion, go to the Chunghwa Post Web site and click on "zip code" 。【3+2郵遞區號查詢】