Line-engraved collecting has its own vocabulary. The following terms are explained in practical language for collectors.
- Alphabet
- The style of corner lettering used on a stamp. Different alphabets help identify the period and issue.
- Basal Shift
- A displacement of part of the printed design caused during the transfer of the stamp image to the printing plate. Basal shifts are most commonly seen in the lower portion of the design, particularly around the check-letter squares and corner lettering. The degree and direction of the shift can sometimes assist with plate identification.
- Blueing
- A bluish discolouration of the paper caused by a chemical reaction between the printing ink and the paper during manufacture. Blueing is most commonly associated with certain line-engraved issues and can be an important aid to identification.
- Check Letters
- The letters in the lower corners of many line-engraved stamps, used to identify the position on the sheet.
- Corrosion Marks
- Marks caused by corrosion or deterioration of the printing plate. These can appear as small coloured dots, irregular lines or roughened areas within the design. In some cases, corrosion marks become constant characteristics of a plate and can assist with plate identification.
- Die
- The original engraved design from which transfer tools and plates were produced.
- Duplex
- A cancellation combining a datestamp and obliterator in one handstamp.
- Essay
- A proposed stamp design, colour or production method submitted for consideration before a stamp was issued. Essays may differ significantly from the final adopted design and provide an insight into the development of a stamp issue.
- Guide Line
- A fine line left from the preparation or layout of the plate.
- Imperforate
- A stamp issued without perforations and intended to be separated from the sheet by cutting. Collectors generally judge imperforate stamps by the size and quality of their margins.
- Imprimatur
- An impression taken from a newly completed plate for official approval before normal production began. Imprimatur sheets are important reference material for plating studies.
- Inverted Watermark
- A watermark that appears upside down in relation to its normal orientation. Inverted watermarks occur when the paper is fed into the printing process the wrong way round and can be an important variety on some issues.
- Ivory Head
- A pale image of the Queen's head visible on the reverse of some stamps.
- Margins
- The blank paper surrounding the printed design on an imperforate stamp. Collectors generally prefer stamps with four clear margins, while stamps cut into the design are usually less desirable.
- Maltese Cross
- The distinctive cancellation used on the earliest British adhesive stamps. Maltese Cross cancellations exist in several colours and many local varieties.
- Mint Hinged
- A stamp that retains its original gum but has previously been mounted in an album using a stamp hinge. Evidence of the hinge may remain on the reverse.
- Misperf
- A perforation error caused when the rows of perforations are applied in the wrong position. Misperforations can result in uneven margins, part of the design being cut away, or portions of an adjoining stamp appearing on the same stamp. Significant misperforations are popular with collectors and can sometimes command substantial premiums.
- Multiple
- Two or more adjoining stamps that remain attached as originally printed. Common forms include pairs, strips, blocks and larger pieces. Multiples can provide valuable plating evidence and are often scarcer than individual stamps.
- Numeral Postmark
- A cancellation containing a number allocated to a particular post office or district. Introduced in 1844 to replace the Maltese Cross, numeral postmarks can often be used to identify where a stamp was used. Separate numbering systems and shapes were used for England / Wales, Scotland and Ireland, allowing collectors to determine the location in which the cancellation was applied. Numeral postmarks are widely collected and many scarce numbers command significant premiums.
- Overseas Postmark
- A postmark applied outside Great Britain to a British stamp. Overseas postmarks are found on stamps used in British post offices abroad, military postal systems, colonial territories and foreign destinations. They are often collected for their historical interest and can sometimes be scarce or valuable.
- Perforation
- The rows of small holes introduced to make stamps easier to separate. Perforation can be an important aid to identification, as different issues were produced with different perforation gauges.
- Plate
- The steel plate from which sheets of stamps were printed.
- Plate Number
- A number identifying the printing plate from which a stamp was produced. On many later line-engraved issues the plate number forms part of the design.
- Plating
- Identifying the printing plate from which a stamp was produced.
- Re-entry
- A strengthened impression made by applying the transfer roller again, sometimes leaving doubling.
- Retouch
- A manual repair or strengthening of part of the design.
- Shade
- A recognised variation in the colour of a stamp. Shade differences may result from changes in ink, printing methods, paper or production period. Some shades are common, while others are scarce and can command significant premiums.
- Specimen
- A stamp overprinted, perforated or otherwise marked "SPECIMEN" for distribution to postal administrations, government departments or authorised recipients. Specimens were not intended for postal use and are collected as a distinct category of philatelic material.
- Spoon Postmark
- A type of duplex cancellation in which the numeral obliterator has a distinctive spoon-shaped appearance. Spoon postmarks were used by a number of post offices and are popular with collectors because of their distinctive designs and local variations.
- State
- The condition of a plate or individual position at a particular point in its life. A stamp may exist in different states before and after repairs or as wear developed.
- Transfer Roller
- A hardened steel roller used to transfer the design from the die to the printing plate.
- Unmounted Mint
- A stamp in unused condition with its original gum fully intact and no trace of a hinge having been attached. Because many nineteenth-century stamps were routinely mounted with hinges, genuine unmounted mint examples can be scarce and highly desirable.
- Unused
- A stamp that has not been used for postal purposes and does not bear a cancellation. Unused stamps may be either mint hinged or unmounted mint.
- Used
- A stamp that has been used for postal purposes and bears a cancellation or postmark. Used stamps are often collected for their postal history, postmarks and plate characteristics.
- Watermark
- A design formed in the paper during manufacture, visible when examined correctly.