Physics. the flow of a gas through a small orifice at such density that the mean distance between the molecules is large compared with the diameter of the orifice. Men who indulge themselves in writing anonymous accusations seldom limit themselves to one effusion.
For US Zip code validation Use below regular Expression. ^([0-9]{5})$. For Canada Postal code validation Use below regular Expression to validate the zip/postal code in your form. ^[ABCEGHJKLMNPRSTVXYabceghjklmnprstvxy]{1}\d{1}[A-Za-z]{1} *\d{1}[A-Za-z]{1}\d{1}$.
From the UPS docs: UPS Address Validation uses U.S. Postal Service guidelines to thoroughly check the city, state and postal code of every shipment. UPS provides up to ten alternate addresses, including an accuracy rate that lets your customers know how closely the address they entered matches the suggested address.