If the filing threshold has been met, or in other words, if, independent of the portability election, the estate is required to file an estate tax return based on the total value of the gross estate and adjusted taxable gifts, no extension of time to elect portability is available and Revenue Procedure 2017-34 does not apply.
Verification is the process of assuring that the product satisfies the conditions before work starts. Validation is the process of assuring that the product meets the specified requirements at the end of the development phase. In other words, to make sure the product is designed in accordance with customer's requirements.
Like AVS, address validation checks an address against a database; unlike AVS, address validation checks the whole address. AVS is only looking for enough information to verify the cardholder's identity, whereas address validation needs to know if mail carriers will deliver a letter or package to an address.