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)

Extra or Supplementary (From Laitn, maidservant)

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

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

Business Reply Envelope.  (See 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.

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.

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

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

A collection of tables that logically go together.