Alternative Address

Refers to the use of either a generic name such as "Occupant" or the addition of an exceptional addressee "or Current Resident" to the address. (DMM 602.3.0)

Ancillary

Extra or Supplementary (From Latin, maidservant)

Ancillary Service
Endorsement

A line of text placed in a specific location on a mail piece to indicate how an undeliverable piece should be handled.  (QSG 507d)

Aspect Ratio

The length of a mail piece divided by it's height.

BRE

Business Reply Envelope.  (See BRM)

BRM

Business Reply Mail.  A mail piece for which the mailer provides the mail piece or envelope and pays the return postage with a USPS business reply mail account.

CASS

Coding Accuracy Support System - A certified process for matching an address to the postal databases, verifying or correcting the ZIP code, and returning the additional information such as the ZIP+4 code that are required for mailings. The software that performs this work produces a document called a "CASS Certificate" that is required for barcoded mailings.

CRM

Courtesy Reply Mail.  A mail piece for which the mailer provides the mail piece or envelope but not the postage, the recipient affixes his own postage before returning.

CSR

Customer Support Ruling - Documents issued by the postal service to clarify their interpretation of the postal regulations.

Data

Plural of datum.  But often used in the singular to describe a collection of datums.