A Glossary of Terms for the Collector of United States Stamps

M - prefix letter used by 3M Corporation in front of the plate number on its modern stamp production.

MDI Booklets - hand made booklets produced by Minnesota Diversified Industries.  Most contained 15 water-activated gum  sheet stamps placed within blue cardboard covers that had a rectangular opening through which the stamps could be seen.  (Other MDI booklets contained self-adhesive stamps that were produced from pieces of web originally intended to be processed into convertible booklets.  With these booklets, special die cut mats were used to create booklet panes or 14, 15, or 16 stamps that were glued into the blue covers.)

MOB - see Money Order Business Cancellation.

MPO - see Mobile Post Office.

*Machine Cancel - a cancellation applied by a machine, as opposed to one applied by hand.

"Mail Early in the Day" - a slogan used as a marginal marking from 1966 to 1978.

Mail Stream - the movement of mail from the moment it is entrusted into the care of the Postal Service until it is delivered to its recipient.

Mailometer Perforations - see Schermack Perforations.

Main Post Office - the primary post office of a city that has secondary post office facilities.  Formerly known as General Post Office.

Make-shift booklets - see MDI booklets.

Make-up Rate Stamp - a nondenominated  postage stamp, intended for use on first class mail, printed in anticipation of an increase in postal rates.  The stamp is equivalent in value to the amount of the increase.  Example: Weathervane stamp of 1998 (Scott 3257).

Manhardt-Alexander - subcontractor to (Ashton-Potter (USA) LTD. for the printing of the 1994 (lithographed American Music Series postage stamps (Scott 2854-2861).

Manila Paper - a coarse, light brown paper used in the manufacture of stamped envelopes.

*Manuscript Cancel - cancellation of a stamp by pen or marker.  Some early manuscript cancellations were applied because the post office had no cancelling device.  Modern manuscript cancellations are often applied in the field to stamps that escaped normal cancellation.  Stamps with manuscript cancellations are considered by some to be less desirable than stamps with other types of cancellations.

*Margin - any printed or unprinted paper on a sheet or pane of stamps that does not contain a stamp.  Marginal markings are found in the margin.

Margin Block - any block of stamps with margin selvage attached.  Frequently (but not necessarily) a marginal marking will be found in the selvage.

*Marginal Marking - any marking found on a plate except for the stamp itself.  Such markings will, of course, also appear on the printed sheet.  Examples of marginal markings include plate numbers, initials, Mr. Zip, and copyright notices.

Match and Medicine Stamps - see Private Die Proprietary Stamps.

Mercantile Corp. - manufacturer of early 20th century stamped envelopes and wrappers.

Merry Widow - nickname for the 1908 green Special Delivery stamp.  Scott E7.

Meter - 1.) a machine that imprints evidence of payment of postage.  2.) the imprint of such a machine.

Microprinting - extremely small words, printed on some modern stamps as a security measure.

Middle West Supply Co - manufacturer of early 20th century stamped envelopes and wrappers.

Miehle Press - 1.) flat plate press first used at the BEP in 1894.  2.) offset press used at the BEP in 1970's

Minnesota Diversified Industries - manufacturer of MDI booklets.

*Mint - a stamp in the same unused condition in which it came from the post office.  Sometimes this term is also applied to unused stamps that have been previously hinged.

Miscut - a freak created when a stamp or pane is not cut in the normal manner during the production process.

Misregistration - see Registration.

Missionaries - a nickname for the 1851-52 stamps of Hawaii.

Mixed Franking - 1.) a cover with the stamps of two or more nations affixed.  2.) a cover with any other unusual combination of stamps used together, such as an Official and a definitive.

Mobile Post Office - post office facility that sorts and distributes mail while in transit, whether by rail (including street car), water or highway.

Money Order Business Cancellation - a circular handstamp cancellation containing the initials MOB; intended for use only on money orders but occasionally used on cover.

Morgan Envelope Co. - manufacturer of 19th century stamped envelopes and wrappers.

Motor Vehicle Stamp - a revenue stamp paying the tax on the use of a motor vehicle.  Scott RV.

Mottled Tagging - tagging with an uneven, rough, or dappled appearance when viewed under ultraviolet light, as opposed to even or grainy tagging.  Some causes of mottled tagging are uncoated paper, worn tagging rollers, and offsetting of wet taggant ink when sheets are stacked.  Example: 1991 Dennis Chavez stamp, Scott 2186.

Mourning Cover - a cover with a black border, conveying news of a death.

Multi-Color Corp. - printing subcontractor to American Banknote Corp. Example: 1991 Christmas booklet.  Scott BK 194.

*Multiple - a unit of two or more unseparated stamps.

*Mute Cancel - a cancel that does not include a date or time.  Generally used on Registered Mail and mail other than first class.

Narcotic Tax Stamps - revenue stamps paying the federal tax on opium, coca leaves and their derivatives.  The tax was in effect from 1917 through 1971.  Scott RJA

National Bank Note Company - holder of the contract to print postage stamps from 1861 to 1873.

*National Defense Issue - set of three postage stamps promoting national defense in 1940.  Scott 899-901.

National Label Co. - subcontractor to 3M for printing of 1994 Eagle stamp (Scott 2598).

*National Parks Issue - commemorative  postage stamp set of 1934 honoring various National Parks.  Scott 740-749.  see also Farley's Follies.

National Postal Museum - a museum of the Smithsonian Institution, located in the old Washington City Post Office, housing the national postage stamp collection.

Nesbitt, George F. & Co. - printer of the earliest stamped envelopes and wrappers.

Never hinged - a stamp with gum undisturbed by the presence of a hinge.

Newspaper and Periodical Stamps - stamps issued to represent payment of postage on newspapers and periodicals.  From their release in 1865 until 1869 the stamps were affixed to wrappers on bundles, not to individual newspapers.  Beginning in 1875 stamps were placed in a receipt book.  These stamps were discontinued in 1898.  Scott numbers begin with PR.

Nixie Clerk - a post office clerk responsible for handling items not readily deliverable because of a deficiency in address.

Nondenominated Stamp - a stamp that does not have a value printed on its face, but does have a value assigned.  Such stamps often have a letter of the alphabet as part of their design that represents the assigned value.  Example: 1978 "A" stamp, Scott 1735, has an assigned value of 15¢.

Nonstandard Mail - First class mail weighing less than one ounce, and that is also of non-standard size or thickness.  An additional charge is imposed for nonstandard mail.

OCR - see Optical Character Reader.

Obliterator - a device that cancels a stamp; may also be called a "killer".

Occupation Stamps - see Allied Military Government Stamps.

Oddity - a broad category of unusual variations.  Examples: stamps used before their first day of issue, errors in postmarks, and semi-official separations such as the Kansas City roulettes.

Off Center - a stamp whose design is not centered in relation to the edges of the stamp.

Offices Abroad - a post office maintained on the soil of a foreign county.  Between 1919 and 1922 the U.S. Postal Agency in Shanghai, China was provided with surcharged postage stamps for use by that agency.

Offices in China - US postage stamps surcharged for use by the US Postal Agency in Shanghai, China.  Scott numbers begin with K.

Official Mail - mail sent by a government agency, using official stamps or a penalty envelope.

Official Postal Cards - postal cards issued for use by federal government departments.  Scott numbers begin with UZ.

Official Stamped Envelopes - envelopes (and wrappers) used by federal government departments in the 1870s and early 1880s, and again beginning in 1983.  Scott numbers begin with UO for envelopes and WO for wrappers.

*Official Stamps - stamps used by federal government departments in the 1870s and early 1880s, and again beginning in 1983.  Scott numbers begin with O.  see also Postal Savings Mail.

Offset Lithography - see Offset Printing.

Offset Printing - a method of printing in which the inked image is first transferred from the printing plate to a rubber roller or blanket.  The inked image is then transferred from the roller to paper.  postage stamps were first printed from offset lithography in 1918-20.  More recent stamps have been produced by a combination of offset and intaglio printing.  Offset printing is usually lithography, but not always.  For example, the Overrun Countries stamps were printed by offset letterpress, sometimes called dry offset or letterset.  The background colors on the 1968 and 1969 Christmas stamps (Scott 1363 and 1384) were printed by offset intaglio.

Optical Character Reader - postal equipment that "reads" the address on an envelope.  Sometimes this term is also used for the entire system, including the device that sprays the address on the envelope as a bar code.

Orangeburg Coil - nickname for the rare 3¢ Washington-Franklin  coil with a vertical perforation gauge of 12.  Used only by a drug company in Orangeburg, N.Y. for a short period of time in 1911.  Scott 389.

Ordinary Stamps - see Definitives.

*Original Gum - gum on a stamp as issued by the post office.

Overall Tagging - Phosphor tagging that completely covers a stamp, as opposed to block tagging.  The clear taggant ink is applied on top of the stamp, as opposed to prephosphored paper tagging in which the taggant is in the paper itself.

*Overprint - printing done on top of a stamp's face for some special purpose.  Overprints have been used for precancelling,  service inscription,  surcharging,  commemorative and security purposes, and on AMGs.  Example: Hawaii Sesquicentennial stamps (Scott 647-8). Precancels.

*Overrun Countries - set issued in 1943-44 honoring countries overrun during World War II.  Scott 909-921.