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The Heidelberg website glossary explains, in alphabetical order, a multitude of terms relevant to printing, as well as some terms used in Heidelberg's product catalogue.

Simply click on the letter of your choice to access the information you need.

TAGA (Technical Association of the Graphic Arts): An international technical association for professionals in the graphic arts industry founded in 1948. Its some 900 members include scientists and engineers from publishing houses, print shops and other graphic arts businesses and suppliers.
Tamper-evident adhesive labels: A kind of adhesive labels that make any attempts to open or manipulate the product visible. Special tamper-evident labels are used, for example, to protect the integrity of packaging.
Template: A guide for positioning pages or parts of pages consisting of a series of lines to indicate final trim size, bleed, head margin, back margin, type page size and other elements.
Terahertz waves: The electromagnetic waves found in the spectrum between microwaves and infra-red light with a frequency of approximately 300 GHz to 10 Terahertz (wavelengths of 1 mm to 30 µm). In addition to fast data communication and measuring applications in atmospheric research and astrophysics, new imaging methods are just one of the future areas of application for this segment of the spectrum. Scientists are working on a method of making the content of books visible without having to open them. This work is intended to make it possible to look at manuscripts that are already so damaged that opening them would destroy them completely.
Tertiary color: A color rendered from the mixing of three primary colors. Examples include brown, olive and ochre.
TeX: Pronounced “tech”; a typesetting program developed by the American computer scientist Donald E. Knuth in the late 1970s specifically for scientific texts. Unlike today's standard layout software, such as Quark Xpress or InDesign, TeX is not based on a graphic user interface, but processes texts containing formatting instructions. The software is available for numerous computer types and uses its own fonts that are developed using the Metafont program.
Text spacing: See "spacing".
Textured inks: Inks with special structures that create their color impression in part or whole by their physical structure and not by their dyes or pigments. Such inks can contain elements that selectively reflect light of a certain wavelength with the aid of interference effects. Textured inks create shimmering color effects that can vary, depending on the viewing angle. This kind of color generation has its model in nature, where it is found in insects and some species of birds. It cannot be reproduced by conventional means, which is why textured inks are often used for documents where forgery protection is desired.
TFT (thin film transistor; liquid crystal display [LCD]): Refers to technology employed in flat screen monitors, in which minute transistor elements control the alignment of liquid crystals in such a way that light is allowed to pass through or is blocked. Within the TFT element, the total brightness and color reproduction are simultaneously controlled. The light for every pixel passes through a color cell consisting of three color filters (red, green, blue), and every filter is equipped with a transistor that can be driven separately and controls the transmittance of light of every color element. See also “LCD”.
Thermochromic printing inks: Inks that change color or disappear completely as the temperature changes, including as a result of brief exposure to body heat. Such inks are used to protect documents against forgery, and as temperature indicators for drinks and medicines, as well as for the monitoring of heating and cooling units. Another application is the indication of potential damage to heat-sensitive products, since certain thermochromic printing inks change color permanently at certain temperatures.
Thixotropy: The characteristic of certain viscous substances to become less viscous through mechanical action (stirring). Thixotropic materials are used in offset printing inks to enhance the quality of multi-color printing. The lower viscosity inks in the inking unit solidify to a certain degree on the printing stock before drying, and additional printing processes are thus optimized.
Three-blade automatic cutting machine: A cutting machine equipped with three blades for cutting products on three different sides. Such machines typically operate in two stages. First top and bottom edges are trimmed, and the third blade then trims the front edge.
Thumb test: Test used to determine the grain direction of paper.
TIFF (tagged image file format): A file format used for images and defined by a computer industry committee in 1986. It is a so-called screen format that contains information on the brightness and hue of every pixel. The TIFF format supports various color systems, from black-and-white to full-color RGB images. TIFF files can be compressed by a variety of methods.
Tissue paper: The term used for various paper grades with a grammage of up to 30 gsm.
Tonal jump: The sudden increase in dot gain that results from color bridges that form between dots. In a tonal gradation from white to black, there is always a specific gray value at which two adjacent dots come into slight contact and join, a phenomenon called touching. The result is that a smooth tonal gradation is destroyed by a visible, harsh transition or “jump”.
Tonal range: Contrast ratio in continuous-tone pictures from the lightest to the darkest tonal values.
Tonal value increase (TVI): The percent increase in the apparent darkness of an image in the mid-tone range during the production run. Example: with 15 percent dot gain, a 55 percent halftone will increase to 70 percent. This increase is compensated for in reproduction by making the image lighter in the color separations. See also “dot gain”.
Tone value (tonal value): A term used in photography and printing for the share of an area that is covered or the effective optical area coverage.
Total ink limit (TIL; total ink coverage [TIC]; total area coverage [TAC]): Value indicating the maximum amount of printing ink needed for the production of colors in four-color and offset printing. Normally the higher the total ink limit, the darker the color to be reproduced.
Tracking: The extension of the character spacing of a font by adjusting the distance between letters.
Tracking system: A system that provides information on the current status of a query or order or determines the location of a product in the manufacturing or delivery process. These systems often form part of an electronic trading system that involves e-commerce. A tracking system can allow print shop customers to follow the progress of their print job over the Internet.
Trapping (spreading): The creation of an overlapping area where two colors adjoin in order to make up for imprecisions in the printing process. See also "knockout".
Trim: The edge of the page of a printed product that actually extends beyond the planned dimensions of the final product. This trim enables all the pages of a book or magazine to be cut to the same size in the final processing stages.
Trimming: The process by which the pages of a book, brochure or magazine are smoothed or evened out. The three unbound sides of a publication are usually trimmed, though in the adhesive binding process, all four sides are trimmed. Trimming also separates the individual pages, so that the book or brochure can be opened.
Trust Centers: An organization which creates digital certificates and serves as a neutral, trustworthy authority to verify the identity of users or clients. The correct allocation of a digital certificate to an individual is guaranteed via a certification server, a type of registration authority, which is part of the trust center.
Type 1 and TrueType: Terminology used to define technologies for displaying fonts on monitors and other output devices. Developed by Adobe, Type 1 defines character shapes mathematically irrespective of size as curves using cubic Bezier polynomials. A program known as a rasterizer generates the characters as screen images in the required size and suitable for the resolution of the output device. The system also forms part of the Postscript system for defining the graphical form of documents and is therefore prevalent in the prepress industry. TrueType is a similar process that is used for Macintosh computers and the Windows operating system. This technology uses simpler quadratic B-splines for defining the characters. There have been attempts to converge Type 1 and TrueType, and as a result Version 3 of the Postscript system now also supports TrueType technology.
Type size: The vertical dimensions of a letter, measured in point or millimeter.
Typesetting: The process by which characters are assembled into formatted text for the purpose of producing print originals. Before typesetting machines were invented, text was set by hand using individual letters of type. The first major revolution in the typesetting world came in 1882 when Ottmar Mergenthaler patented the Linotype line composing machine. In the second half of the 20th Century, typesetting moved increasingly towards photocomposition. Today, typesetting and page make-up are largely computerized in the form of “desktop publishing.”
Typographical system of units: A measurement system originally developed by the Parisian typecaster Pierre Simon Fournier in 1737. The basic unit is the typographical point (abbreviated p), where 1 meter = 2660 points or 1 point = 0.3759 millimeters. Other units are the nonpareil (6 points), brevier (8 points), cicero (c) (12 points) and canon (48 points). These designations stem from type sizes which originally had their own names. The restructuring of the measurement system in Germany in 1977 brought an end to this system, though it continues to be used in a modified form. The units have been rounded to 5/100 millimeters.
Typography: The study of the design and use of type, the objective of which is to make text as legible and visually attractive as possible, by choosing appropriate typefaces, font sizes and attributes, but also by means of page layout. The rules of typography for paper are so well developed that further improvements scarcely seem likely, though this is not yet the case for other media such as computer monitors and electronic displays.

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