Mailing Evaluation Readability Lookup Instrument.
Someone went to some lengths to justify calling a machine MERLIN. In 2001, the USPS began using MERLIN machines to help automate the intensive process of verifying eligibility for bulk mail discounts. This magical marvel of modern wizardry analyzed samples of mailings consisting of 10,000 or more pieces — weighing and measuring them to make that [none] of these things were not like the others. MERLIN retired (or perhaps was lured away by the Lady of the Lake) in 2009 when the USPS switched to a performance based verification system. I would have stuck with the wizard, myself.