Home Contents Credits


Below are some of the terms I have used in these pages that I felt needed explanation. If I've left something out, please email me, and I will add it. Or consult one of the excellent reference works I have listed here.

Please note that this glossary is not intended to be exhaustive.
There are other excellent, far more extensive philatelic glossaries on the WWW,
for example, one by the United States Stamp Society, at http://glossary.usstamps.org/,

Google can guide you to others.

Note that I have tried not to clutter this page with images. Instead, I have provided links, either directly to example images, or to other pages with images.


AIGA - The American Institute of Graphic Arts, an organization devoted to promotion of the Graphic Arts in the U. S. Its San Francisco chapter sponsored the development and production of this philatelic alphabet.

Balloon Mail

Balloon Mail - Mail carried by balloon, often in a time of siege, or to create souvenirs of the occasion. The earliest recorded examples were in 1793, while the most famous was probably the Siege of Paris of 1870-71. In the U. S., the Balloon Jupiter, in 1859, was a pioneering effort to use a balloon to transport mail. The almost complete unpredictability of balloon travel rendered it extremely impractical for ordinary mail, and prevented its ever developing past the status of a curiosity.


BEP - Bureau of Engraving and Printing, the US government department, founded in 1862, that produces all US currency and, from 1894 until 1979, all of its stamps. When I first wrote these pages, the BEP still printed stamps, but in 1997 for the first time since 1894 it produced less than half the total - about 46%, and I read recently that by the end of 2005 the BEP will no longer print U.S. stamps at all.

The BEP has a great web site - here.


Bluenose - Classic Canadian stamp issued in 1929, and generally considered the most beautiful Canadian stamp ever produced, with the perfect combination of design, engraving, and color. I think it is one of the most beautiful worldwide.


"Centering" for a stamp refers to how well the design is centered relative to the perforations. Most stamps have a rectangular design, with a blank area around it, and then the perforations. In modern stamps the design is usually well centered, but in older stamps, especially those produced before 1900, centering was often quite poor. Here are some examples:

Those four stamps were printed in 1861, 1868, 1863, and 1868 (l to r), and exemplify pretty well the extremes of centering that were not uncommon at the time.

Centering is usually described by philatelic experts with initials such as F, VF, XF. Here are the terms used, and their general meanings:

G = GOOD. This means the stamp is seriously off center, with the perfs cutting into the design. For anything but the rarest stamps, where there are so few that any condition is acceptable, stamps with GOOD centering are considered little more than space fillers. Some people call this grade AVERAGE.
F = FINE. This means noticeably off center on two sides, but the perfs touch the design only slightly or not at all.
VF = VERY FINE. This means the stamp is well centered, but not perfectly so. It is a bit off center in at least one direction, but still attractive.
XF = EXTRA FINE. This means the stamp is perfectly centered.

Note that the worst centering is not called POOR or ABYSMAL, which would be far more accurate. Descriptions are always at least a bit exaggerated.

SO WHAT ABOUT THE FOUR STAMPS ABOVE? The second and fourth have G centering, the first I would call VF, and the third I would call F. This is not a science, and has a big effect on a stamp's value, so a seller is almost certain to evaluate the centering of his stamps better than a buyer. You will see grades such as F-VF, meaning FINE to VERY FINE, and implying that the stamp is not quite VF, but certainly better than just F. On such minute distinctions rest big bucks. There is also SUPERB! And let's not forget GEM! Those imply the Best of the Best, a stamp that is the finest imaginable for its issue, and a true GEM can sell for many multiples of its catalog value.

"For its issue" - that brings up one last important point about centering. In those early days when centering varied so wildly, some stamps that were printed in small quantities, or with very narrow margins, simply don't occur with centering even as good as VF. SO you will see descriptions such as "XF for this issue!" attached to stamps that are really only F. The seller is trying to tell you this is about the best you'll get. If you trust him, fine. I suggest you look up the stamp in Datz's The Buyer's Guide. He gives precise statistics about all the early US stamps, with illustrations of typical centering, so you can be your own judge of how well a specific stamp compares to the standards for its issue.

Here's more about centering, and its effect on a stamp's value.

Center Line Block

The center line block is a block of four from the center of a sheet of early 20th century US stamps, with horizontal and vertical guidelines running through the perfs, or through the center of the blank space between the stamps. It was used for two different purposes on flat plate engraved stamps of the U. S.

On single-color definitive stamps, which were printed in sheets of 400 (20x20), the guidelines showed where the sheet was to be cut into panes of 100. We have center line blocks because unperforated sheets of many definitives in the years from 1906 to 1926 were sold to private parties for conversion to coils (see the plate diagrams on my K is for Kansas City Roulettes page - everything you see on the left-hand image there would have printed.)

Bi-color stamps like our first airmail stamp, the 24¢ Curtiss Jenny stamp of 1918 (Scott C3), were printed in sheets of 100, and had to be printed in two steps, one per color. The guidelines helped align the plate for printing the second color. Unfortunately, they did not guarantee correct up vs. down orientation, and the plates used for the first printing of the 24¢ Jenny had no other markings to help show top vs. bottom. Under the pressures of time and efficiency, at least one sheet was printed with the centers inverted. After that sheet of 100 of the Inverted Jenny was found, TOP was added to both plates for subsequent printings. (see my I is for Invert Error page for a picture of the Inverted Jenny.)

Civil War

If you grew up in the South, as I did, you know that the proper term is not "Civil War", but "The War Between The States".

"CSA" stands for Confederate States of America, the official name for the South during the War.

In the North, the official name for the Civil War was "The War of the Rebellion"!

The Internet is full of great Civil War web sites - try your favorite search engine.

Here's a fascinating page titled The Confederate Postal Operations - Adding Order to a Time of Chaos and Disorder(!)

Examples of some Civil War era postal material can be found on my own W is for War, A is for Advertising Cover, and Trains on U.S. Advertising Covers and Patriotic Covers pages.

Commemorative stamp

A Commemorative stamp is one issued to honor a person or event. It is printed once, in relatively small quantities (typically 50 to 100 million in the U.S.), and withdrawn from sale (if not sold out) after a specified time, usually about a year. Or at least that's what it used to be - these days, with stamps for insects, aquariums, and dinosaurs, the definition has been stretched quite a bit. They usually make at least a pretense of a connection to U.S. history or culture, but let's face it, the name of the game is "market appeal". Here is a page with images of some U.S. commemoratives.


A cover is any postally used envelope, usually with an address, a stamp, a cancel, a postmark, and perhaps other postal markings. Many of my pages show examples of covers - try A is for Advertising Cover.

Definitive stamp

A definitive stamp (as opposed to commemorative, special, or service-specific stamps) is one issued as a work-horse of the postal system. Usually small in size (so many will fit on a pane), and with a patriotic (e.g., a flag) or generic (e.g. "Transportation") design, it is printed in huge quantities (billions), and reprinted as needed (unlike a commemorative, which usually gets only one printing), and may stay in service for many years - some in the U.S. have lasted over two decades.

Durland Catalog

The Durland Catalog is published periodically by the United States Stamp Society (formerly the Bureau Issues Association), and lists all known plate numbers on U.S. stamps. That may seem like useless information, but in fact has several important uses for collectors. For one thing, its plate number can be used to authenticate a stamp, since plate numbers are unique to a design and (usually) format. For another, some people collect plate blocks, i.e. the block of four (or on some older issues, six or eight) stamps adjacent to the plate number, and need to know what plate numbers were used, and in what quantity, since rarer numbers command a high premium.

If the topic of plate blocks interests you, I've written a little about them, here


I've made reference throughout these pages to the presence of fakes and forgeries in the philatelic marketplace, and the importance of being cautious when buying expensive material - see especially Q is for Quality.

An expertization certificate is a form of insurance. Someday you or your heirs will want to sell the items you have collected, and a certificate helps guarantee that a prospective buyer will be willing to pay some reasonable percentage of what you did.

The way you obtain a certificate is fairly simple - first you need a request form from the service you wish to use. There are several general expertizing services I know of in operation in the US right now, and many other specialized ones. The next section of this document gives the names and addresses of two of the major ones. Write for a certificate, which will explain as well the terms. They all charge a fee, either a percentage of the item's value, or a flat fee per item.

Follow the instructions on the form, and send it in, then be patient. These things take time. Four to six weeks is typical.

A certificate is not a guarantee, however; new technology and information have led to revised opinions about some material, in both directions - items once judged authentic may now be judged fakes, and ones rejected as fakes may be accepted as valid, though the latter is far less likely - you can count on the experts to be cautious and conservative - if they are not sure, they will say so, and give a "No Opinion" certificate.

The most frustrating thing for me about getting a certificate is that it never says exactly how the experts reached their decision. Depending on the item, its value, and the complexity of the judgment, a service will submit your material to just one expert, or to as many as three or four. Most services have a reference collection of material known to be both genuine and fake, for comparison with items submitted for expertization. Some also have sophisticated modern equipment that allows them to analyze the item with special light or to analyze it chemically to reveal key features. And you may assume the experts have seen a lot of real items and fakes, so they know what to look for.

The bottom line for me is this:

1. I always try to authenticate tricky material first myself, if only to learn a little more about it. Understanding how to expertize my own material and what makes the difference between the real thing and a fake increases my enjoyment of the hobby, and helps protect me from costly mistakes. In addition, if I find it difficult to decide what something is, I am better able to appreciate the efforts of the experts I consult.

2. I avoid questionable material. If I have trouble finding the feature that distinguishes a variety - a watermark or design element, for instance - I pass the item by. Even if the experts say it is genuine, I prefer to own something that exhibits its distinguishing marks as clearly as possible. This does not mean I don't need a certificate for that item, of course. If there's money to be made faking it, someone will do it.

Expertizing Services

American Philatelic Expertizing Service. Go to their website, or write them at -

P.O. Box 8000
State College, PA 16803

American Philatelic Society members get a discount from the APES, so joining that organization can save you money if you need a lot of certificates.

One excellent source of information about how expertizers work, and the methods that are used to authenticate stamps, is the recent series of articles by Mercer Bristow, Director of the APES, in Stamp Collector (which is sadly now defunct (7/4/4).


The Philatelic Foundation is one of oldest collector organizations in the country. It has one of the best reference collections in the world, and offers one of the most respected expertizing services. There is another organization called the "American Philatelic Foundation", which does have a web site - it has no connection with the PF.

The Philatelic Foundation
70 West 40th Street, 15th Floor, New York, NY 10018
Telephone: (212) 221-6555; Fax: (212) 221-6208.
Email: philatelicfoundation@verizon.net

Web site


The Confederate Stamp Alliance specializes in CSA material. Applications for authentication and/or applications for membership are available from:

Patricia A. Kaufmann,
CSA Recording Secretary
522 Old State Road
Lincoln, DE 19960-9767

Link to Web site

First Day Ceremony Program

Most stamps issued by the USPS are announced several months in advance, with a specific issue date and city or town of release. At the designated place and time, a First Day Ceremony is held - some are very simple, others quite elaborate. Official USPS Programs are handed out free to attendees at the First Day ceremonies. These programs - which also vary from plain to fancy - always contain a copy of the stamp being released, with a first day cancel, and a list of the dignitaries attending. The programs are a moderately popular collectible, and most are quite affordable, with prices in the $5 to $20 range. The most desirable copies are ones that have been autographed by the famous names in attendance. I have one I prize from the 1997 Thornton Wilder stamp FD ceremony with Carol Channing's autograph - she starred on Broadway in "Hello Dolly", which was based on a Thornton Wilder play, "The Matchmaker". For some stamps issued in the past few years, the programs have been available by mail from the USPS Philatelic Fulfillment Center, but as with many practices of the USPS, there is no consistency to this. Recently (starting mid-2000), the ceremonies and programs have been severely down-scaled, as part of a USPS economy drive. The programs are now mostly very plain and unadorned.

Free Frank

The term "free frank" is often used today to describe the privilege granted to all Congressmen, to send their mail free of postage. They simply sign the cover where the stamp would go, or stamp their signature there.

But "free frank" is actually redundant, since the verb "frank" means (according to my dictionary) "to mark (a letter, package, etc.) for transmission free of the usual charge, by virtue of official or special privilege". Presidents, members of Congress, Postmasters, and other government officials have long had this authority - their signature serves in place of a stamp to prepay their official mail, so one says they have the "franking privilege".

A more appropriate use of the term "free frank" is when applied to soldiers' mail - in most wars since the US Civil War, soldiers on active duty could send mail without postage by writing either "Soldiers' Mail" or "Free" in the top right corner. One of the many valuable accomplishments of the Universal Postal Union was the institution of this Free Frank privilege for servicemen in time of war and the unobstructed passage of such mail between combatants, though the implementation of this system has not always worked smoothly.

Click here to view a page about the history of the franking privilege.


"Freshness" is one of the important factors in evaluating a stamp's condition. Some others are GUM, CENTERING, and PRINTING.

The ideal stamp is "Post Office fresh!" meaning it looks just as good as it did when it was first purchased, or better yet, when it was printed. The paper is fresh and soft, not browned or brittle; the gum is fresh, not browned and cracked; and the image is clear, crisp, and unfaded. All of those elements combine to define a stamp's Freshness. Sometimes you have to look at a lot of examples of a stamp, to appreciate what true "freshness" is. A stamp may look faded, but that could be just the way all of the issue was printed. The paper may look toned, but that could be just the paper it was printed on. So you have to look at a lot of stamps before you can safely evaluate just one.


"Grills" are a sort of embossing that was applied to US stamps as a security measure during the period from 1867-1872. All or part of the surface of each stamp was impressed with a grid of small indentations that were intended to break the surface of the paper and cause it to absorb a cancellation so that it could not be washed and reused.

This was but one of many such schemes attempted by the USPOD in this early era of postage stamp production. Whether they were really necessary - or merely the result of someone's paranoid fantasies - is debatable. None of them proved worth the time and trouble, nor lasted long.

GUM - Hinging - Gum Condition

It surprises many people initially when they learn that the condition of the gum on a stamp affects its value to a collector, but it's true.

Think of it this way - while it seems silly for a stamp worth only a dollar or two, if you are going to spend a hundred dollars on a tiny scrap of paper, you should get the best example of that scrap of paper you possibly can. And stamps worth a hundred dollars - and much more - are not uncomon. Therefore the ideal stamp is post-office fresh, with bright color, a crisp, perfectly centered design, sharp perforations, and fresh unmarred gum. With early stamps, most of which have suffered some sort of wear over the years, small variations in each of those features can have significant affects on the value (see Q is for Quality)

Stamp Collectors have developed a special vocabulary to describe hinging on stamps -

NH means "Mint, Never Hinged", and is often indicated (in auction catalogs, for instance) by a pair of asterisks (**). It means the stamp is unused, and its gum has absolutely no disturbance of any sort. Post Office fresh. You will often see "MNH", for "Mint, Never Hinged", but to me that is the same as "NH" - the "M" is just for emphasis.

LH means "Mint, Lightly Hinged", and is often indicated (in auction catalogs, for instance) by a single asterisk (*). It means the stamp is unused, but has been hinged, and the hinge removed, leaving a discernible mark on the gum, but only a slight one. You may see "VLH", for Very Lightly Hinged, implying that the trace of hinging is being mentioned only for strict accuracy.

H means "Unused, Hinged", and usually implies a good deal more than just lightly hinged, i.e. there are probably hinge remnants on the stamp.

HR means "Unused, with Hinge Remnants", and you can be fairly sure the back of the stamp is a mess, with heavily disturbed gum and parts of several messy old hinges.

OG means "Original Gum", and is often used to avoid more precise terms. It means the stamp is unused, and has at least some of its original gum, but is probably hinged or heavily hinged. You may see "partial OG", meaning the stamp has lost most of its gum somehow, but still has a little. Terms like OG are salesman's terms, ways of trying to make a stamp look better than it is.

DG is sometimes used as well, and means "Unused, with Disturbed Gum", which does not mean the stamp needs a psychotherapist, but that the gum is not pristine, and none of the other terms describes its condition accurately. There should be no hinge remnants.

Sweated Gum and Glazed Gum are basically the same, and describe the result when stamps are stored under too much heat and/or pressure, melting the gum into a very smooth, shiny condition that reduces the value as much as hinging.

Watch out for stamps with hinge remnants and/or heavily disturbed gum, as these can conceal much more serious defects such as tears, thins, repairs, etc. Any stamp that is heavily hinged loses at least half its catalog value at once, and may in fact qualify as no better than a space filler. And keep in mind that anyone selling a stamp will always try to downplay its defects, so one man's "VLH" may be another's "H". Terms like "virtually" and "almost" are often used to stretch the truth a bit.

For more on the value of stamps, see my Q is for Quality page, and my page on The Economics of Stamp Collecting.

Locals, Agents, Provisionals, Carriers, Expresses, and Forwarders

The period immediately before and during the early years of postage stamps in this country was particularly rich in interesting and often short-lived experiments in how to prepay and deliver mail. All the postal mechanics and procedures we take for granted today - for printing, distributing, selling, and processing stamps and stamped mail - had yet to be developed. Home delivery of mail did not exist - one had to drop mail at and collect it from designated places. There were not even post offices as we know them - collection and delivery points were public meeting places such as hotels and public houses.

Even after the successful experience with the first postage stamps in Great Britain in 1840, the U. S. was not convinced the idea would work here, partly because it required postal reform, including lower standardized rates, which many feared would bankrupt the government. But in 1845 Congress enacted a major standardization of the postal rate structure, and Postmasters in the largest cities, starting in New York, sought and received permission to create their own stamps - these were the Postmasters' Provisionals, which were replaced in 1847 by the first official Government issues.

During the same period, private and public organizations were developing the ideas and tools that would evolve into our modern mail system. Many of them created stamps, i.e., adhesives or handstamps to record the payment of fees. The collection and study of these items, on and off cover, is a fascinating and rewarding specialty.


A local is any private mail-carrying entity, and the term is sometimes used to cover all the more specific terms discussed below. The true Locals were private companies operating in larger cities to provide local pickup and delivery of mail strictly within their city, mainly or at least partly independent of the Post Office. Many issued their own adhesives.

Carriers were individuals or companies who provided the missing link between individuals or businesses and the Post Office - they charged a fee to take mail to the nearest Post Office or to collect it from one and deliver it to the addressee. Some issued adhesives. The early ones were independent, but starting in the early 1840's many were absorbed by the Post Office Department. From the 1850's through the 1890's (?) Carrier service remained a premium service, even when provided by the USPOD.

Expresses were companies operating over longer distances, between cities, to provide service in competition with the mails, or to offer services (such as package delivery before the advent of Parcel Post) the Post Office did not. Their equivalent today is organizations such as UPS and Federal Express. Their attraction then, as now, was the ability to provide faster service. Some issued adhesives to show payment of fees.

Agents were individuals who acted on behalf of the Post Office, usually in connection with a boat or train. They collected mail and fees at a departure point, or en route, added markings such as "PAID" and other postmarks and cancellations, and entered the items into the mailstream. They did not issue their own adhesives.

Forwarding Agents thrived during the period from 1820 to 1860, and served as the collecting and routing mechanism for international mails. Many added their own markings to the mails they handled. To my knowledge they did not issue their own adhesives.

To learn more about Carriers, Locals, and Expresses, I suggest you start with the Siegel Auction Galleries Encyclopedia entry on the topic.

"On piece"

Philatelists use the term "on piece" to describe a cancelled stamp on a piece of paper, usually a corner cut from an envelope, and ideally including all of the postmark/cancellation. A stamp may also be "on cover", i.e. on the entire envelope it paid to mail.

Pane vs. Sheet

A pane of stamps is the largest quantity of stamps you can buy at a post office. Many people mistakenly call this a "Sheet of stamps", which actually means a larger multiple, of four or six or eight or even more panes, and corresponds to the size of the plate used to print the stamps.

You can buy full sheets (also called Press Sheets) of many modern stamps through the USPS Philatelic Services Division, headquartered in the salt caves in Kansas City, at 1- 800-STAMP-24.


Pasteup is a term used to describe a process used in creation of early coil stamps, which were created in a manual operation that required trimming and pasting strips of stamps together to form longer strips. The longest contiguous strip of stamps one could obtain at the time was twenty, so every twenty stamps in a coil of stamps there would be a Pasteup or Pasteup pair, where two strips had been joined. Some collectors of early coils like to collect these as significant varieties, while others avoid them. For more information on how pasteups were created, see this.

Perforations - Unperforated vs. Imperforate vs. Misperforated

"Imperforate" means a stamp was issued without perforations, a practice that was common in the earliest days of stamps, and again for a period in the US at the start of the 20th century, when private companies converted unperforated sheets to coils for use in their proprietary vending and affixing machines.

"Unperforated" means a stamp failed to receive the perforations it should have had, and was released that way by mistake, constituting a production error.

"Misperforated" means a stamp has perforations, but they are so poorly aligned with the design that they constitute a production freak. The line between "poorly centered" and "misperforated" is somewhat a matter of personal judgment.

Despite all the above, few people use "unperforated". The common term for a stamp issued "unperforated," in error, is "Imperf Error". So much for precise terminology.

Plate Blocks

I started collecting when I was eight or ten, when someone gave me a starter set for Christmas. My Dad's boss heard I was collecting, and started sending home plate blocks of new issues. That hooked me - free stamps, and in a format I found mysterious and appealing. I eventually accumulated a U. S. plate block collection for every issue from about 1910 on, and then decided I had too much money tied up in my collection, so I sold it off. But I still love plate blocks and other multiples for what they reveal about stamp production methods and their development.

A plate block is the block of four (or on some older issues, six or eight) stamps adjacent to the plate number on the pane of stamps you buy at the Post Office. Those numbers exist on most stamps produced in this country since 1894, when the BEP took over production of U.S. stamps. Prior to that time, stamp production was performed by private companies, and there was no official policy about plate numbers, so some sheets of stamps had them, but others did not. Most did have some sort of marginal inscriptions, such as the name of the company that printed them.

Plate numbers were added to stamp plates as both a security device (sort of like serial numbers on money), and as an accounting device (to help in keeping track of how many times a plate had been used, for example).

The study and collection of plate blocks is an interesting specialty area. Some people try to obtain an example of every plate number, while others are content with just one per issue. Until a few years ago, plate blocks were relatively scarce, since there was usually only one per pane of fifty or one hundred stamps. Recently the USPS has started putting a plate number in every corner of even small panes of twenty, so plate blocks have little scarcity value, and have lost their appeal to many collectors.

The exception to the rule that all stamps since 1894 have plate numbers was the Overrun Nations set of 1943, about which you can learn a little more here.

Other pages in my web site where I mention (and show examples of) plate blocks are F is for Firsts, H is for Handstamp, I is for Invert Error, Durland Catalog, Knapp FDCs.

Postal Markings

Postal Markings include handstamps, machine markings, hand notations, x-cancels, etc., i.e. any officially applied marking on a stamp or cover, to cancel the stamp or provide some sort of record of its cover's progress through the mails.

"CDS" stands for Circular Date Stamp, the most common sort of postmark put on letters to record their time of entry into the mailstream, or of their receipt at some point along the way.

"PAID" was a common marking up until 1850 or so. Prior to that time, most mail was sent DUE, i.e. the recipient had to pay the postage. In the rare cases when the sender pre-paid the postage, a PAID marking was applied, usually with the amount prepaid, e.g. "PAID 5", for prepayment of 5 ¢. (See the section below on "Stampless covers" for a couple of stories about how people used and abused the DUE system.)

"Cancels" today are the bars or lines to the right of the CDS that "cancel" the stamp, i.e. deface it so it cannot be reused. In the 19th century cancels were often either very crude blobs that totally obscured a stamp's design, or Fancy Cancels with wild and wonderful shapes representing anything from a bird to a death's head.

"Postmarks" are the city, date, and time stamps (usually in a circular border, therefore a Circular Date Stamp), applied to mail to indicate the place and time when it entered the mail stream.

PRINTING - Printing Quality

One of the factors in evaluating a stamp's overall condition is the Quality of Printing. Especially in the early days of US stamp production, the quality of the product varied tremendously. Printing plates were expensive to produce, so they were used as long as possible, and the difference in the sharpness of the impression on an early printing versus that on a late one can be dramatic. Ink was mixed and applied by hand, so the amount, color and distribution all varied. The best way to understand this is to look at a lot of stamps, and see the differences for yourself. The most valuable stamp will have a sharp, crisp, bright impression, while its lesser brethren will look faded and muddy.


Occupational title, engraving - person who operates the machine that transfers dies to plates, and supervises mounting and unmounting of plates on presses. Many U. S. stamps printed in the early twentieth century have initials in the sheet margins, sometimes many sets. The Siderographer's initials occur (usually) only once per plate, and are usually in the lower left corner, put there when the process of "rocking in" all the individual stamp images was completed. The Plate Finisher's initials were added in the bottom right corner, and also occur (usually) only once per plate, as the Plate Finisher did the burnishing and polishing of the plate after the Siderographer did his job. Up until 1911, Plate Printers added their initials to the plate as well, one set each time the plate was checked out of the vault for use, so there are often many different sets. The images below are typical examples of plate printers' initials. I'm not sure why, but the majority of the good examples I have seen are from the Pan-American Exposition issue of 1901, and primarily for the plates used to print the vignettes (center of the design), in black. Perhaps most other plates were larger, so the initials were printed in a part of the selvage that was cut off and discarded?

For more on the subject of plate initials, take a look at the excellent web site of Doug D'Avino, at http://home.earthlink.net/~davinod/Initials.htm . My thanks to Doug for his assistance in my getting this writeup right - on the subject of multiple Siderographer initials on one plate, an uncommon but occasional practice, he wrote me -

There are a couple of instances of multiple Siderographer initials on a plate... It is suspected that: 1) The second set of initials came from an apprentice or 2) Schedules were tight so another siderographer finished the job (perhaps after it was proofed and had to be corrected). On my site, Charles Vermeule and Harold M. Clarvoe have both initialed a single plate as siderographers.

Service-specific stamps

Service-specific stamps are ones issued for a specific type of mail, such as Air- mail or Priority Mail. They are like definitives, in that they may be reprinted as needed, and remain on sale for an indefinite period of time. Today they can be used for any mail, their use is not restricted to the service for which they are issued, but up until about thirty years ago that was not the case - an air mail stamp could be used only for air mail postage. See also commemorative stamps and special stamps.

Special stamps

Special stamps are ones that fit into none of the other categories(!) They aren't quite definitives, they're not commemoratives, and they are not service-specific stamps. They include Christmas stamps and Love stamps and miscellaneous other issues that are printed in relatively large quantities, may be reprinted as needed, and may remain on sale for several years. Sounds like a definitive to me, but someone decided not.

Stampless Covers

The term "Stampless Cover" usually refers (for U.S. postal history) to mail sent before the introduction of postage stamps in 1847. Up to that time, letters could be sent either Prepaid or Due - the latter was most common - and the amount of postage was marked in pen or with a handstamp on the letter. Mail carriers had to collect the postage from the recipient if it had not been prepaid.

The collection and study of stampless covers is a popular branch of philately. Features that make a stampless cover appealing are what postal markings it carries, the source and destination of the letter, whether prepaid or due, and the rate charged.


There is a story that Rowland Hill, the man credited with the establishment of cheap postage and the use of postage stamps in Great Britain, was inspired to develop the concept by witnessing a scene in a country village - the postman presented a letter to a village maiden, who glanced at it, then handed it back, saying she could not afford to pay the postage. Hill, in sympathy, paid the postage and handed it to her. Once the postman had left, the girl confided to Hill that she did not want the letter at all, since the message it conveyed was written in a private code on the exterior, and she had read it when the postman first handed it to her. Whether the story is true or not, it illustrates the major weaknesses of the older system, in which rates were very high, so most mail was sent Due, and the recipient was under no obligation to pay it.


Even after the introduction of postage stamps in the U.S., their use was not mandatory for eight more years. One famous consequence of this was that in 1848, Zachary Taylor did not know he had been nominated for President for several weeks after the nomination took place, until someone arrived to tell him in person - he had refused several letters conveying the news, because he did not care to pay the postage due! This seems incredible in these days of instant world-wide communication, but demonstrates not only the disadvantage of the postage rules in effect at the time, but the different attitude of those times - people valued their privacy. It must be said as well in the famous man's defense that he had been forced to instruct his postmaster to reject all unpaid mail. Taylor was receiving so much from admirers that the cost of the postage due was more than he could afford to pay! Moreover, he had not sought the nomination, and was not expecting it.

The term Stampless Cover applies as well, technically, to any other sort of cover sent without a stamp, such as Soldiers Mail and Free Franks, but its use is generally understood to mean covers from the pre-stamp period.

Prepayment of postage became mandatory in the US in 1855.


Tagging is a chemical substance used to coat a stamp (or as a component of its ink or paper) that reacts to Ultra-Violet light by glowing. The purpose is to make stamps easier for automated facer-cancellers and sorting machines to detect. The US started using tagging on its stamps in a test mode in 1963, and since 1974 has used it on all stamps. Most foreign countries now use some form of tagging as well.

To see tagging on US stamps you need a short-wave UV lamp, which you can buy from any philatelic supplies dealer. The cheaper lamps, which cost as little as $35, may require total darkness to reveal the subtler types of tagging. A more versatile lamp can cost as much as $200.

Be very careful when using a UV lamp, as the light can damage your eyes if you look at it directly, and the human eye cannot detect UV light, so you will have no warning. You should be safe viewing the effects of UV light on your stamps, however, as that is merely reflected light.

Some collectors specialize in the collection and study of tagging varieties. In the early years of tagging on U.S. stamps there were several different styles in use, including overall, and blocks of different sizes. Today most tagging is part of the paper or of a surface coating on the paper.


Thermography is a specialty printing process in which a powder of ink and resin is deposited on paper and then fused with heat into a raised, usually glossy, enamel- like design. It is sometimes mistaken for engraving, which can also produce a raised design, especially when printed on coated paper.

Wheel Arrangement Notation System

Some of the train references in these pages include notations such as "4-4-0" in the locomotive description. These are a shorthand to describe the wheel arrangement of steam locomotives. The system used in America is called the Whyte system. There are three (occasionally four) numbers - the first represents the number of leading or pilot carrying wheels, the second the number of driving wheels, and the third the number of trailing carrying wheels. The drivers are usually much larger than the others, and are the only essential wheels. So you could have an 0-4-0, but never a 4-0-4! You can read more about the Whyte system HERE .

The Europeans use a different system, with a combination of letters and digits, and even we Americans have a separate one for diesels. You can read more about the European system HERE and HERE .

Home Contents Credits

All Letter images Copyright © 1997, 2000, SF chapter of AIGA
All text Copyright © 2000, William M. Senkus

Send feedback to the author: CLICK HERE

Revised -- 02/27/2007