Glossary of Computer Terms

This glossary covers much of the terminology that you will encounter when you work with CD-ROM discs and disc duplicators. Many of these terms are used in this book, but some are not; these are included to help you when you read further in the field. These terms are taken from a number of sources, including the publication "A Glossary of CD and CD-ROM Terms" by Disc Manufacturing, Inc. that is listed in the references; the publication is available from the company at the address in the preface.

Acrobat

An electronic document technology from Adobe Systems that includes the PDF file format, translators for creating PDF files, and readers for displaying PDF files on the screen. Acrobat is built on PostScript and provides faithful electronic displays of fully formatted pages, along with access to other media.

Active area

An area on a screen that can respond to a mouse click or other event to produce an action.

Active region

The portion of a window in which the window's document is presented.

Active window

The window in which program input and output are occurring. In most personal computer systems this will be the topmost window, but this need not be the case.

ADPCM

Adaptive Differential Pulse Code Modulation, a method of storing digital samples based on correlations between successive values. This is a compression technique as well.

AIFF

A sound file format primarily associated with Macintosh and Silicon Graphics computers.

Alpha

The first version of a product or title that is made available for testing or for external examination. This version will usually be incomplete or have known weaknesses, but it will have enough functionality that reviews can help shape the product.

Alt keys

Keystrokes that are formed on the PC by pressing the Alt key together with another key; these keystrokes are a primary means to execute commands from the keyboard. See Command Keys.

AMSTeX

A particular version of a TeX macro set that is used by the American Mathematical Society to typeset their publications. See TeX.

Animation

A moving image created by a sequence of individually computed frames, each of which is crafted separately.

Animated cursor

A cursor that changes its form through time, often used to indicate that some processing is being done.

Animated icon

An icon that contains a sequence of images that are displayed successively, giving the illusion of motion within the icon.

Applet

An application designed to be downloaded to a user across the networks, with the implication that it is a modest-sized application intended for a special purpose.

ASCII (American Standard Code for Information Interchange)

A standardized way of representing text and control characters in one byte each.

Aspect ratio

The ratio of the height to the width of an image.

Assets

The resources an author or developer has to bring to a title. This can include things such as interface objects, images, movies, or text.

Attribute

A property of an object, such as an icon for a document, a color or shape for a button, or font or size for text. Attributes can be set in an authoring language and may be changed by a user.

Author

The person whose creative ideas shape a title and who may create significant pieces of the title's contents.

Authoring language

A system or application used to create an electronic document and define its contents, functionality, and interface.

AVI

Audio Video Interleaved, a file format defined by Microsoft to be used by Video for Windows. This format interleaves sectors of video data and sectors of audio data so that the video player can maintain both audio and video data streams with only minimal data buffering.

Back

To return to the previous screen or state of a document.

Bandwidth

The amount of information that can be transferred in a given time over a communications line, a network, or a device connection.

Baud rate

The rate at which characters are being transmitted over character-oriented communication lines. Usually associated with modem-based communications over telephone lines.

Beta

The second level of release of a product or title before the final release to manufacturing. This level is essentially complete and has the most glaring bugs removed, but may still have minor problems, and is the final level at which testing can occur before release.

Birefringence

Double refraction (of light). Plastic materials, such as a CD substrate, demonstrate this double refringence ability due to residual stresses remaining in the plastic from the molding process. High birefringence can interfere with the laser beam of the reader and cause reading errors.

Bitmap

A two-dimensional array of pixels that is the computer's internal representation of an image.

Block

A segment of data; on a CD-ROM, same as a sector. On CDs, data is arranged in blocks that contain header and sync, user data, error detection and correction, and control information.

BMP

A device-independent graphics file format developed by Microsoft that supports images in as few as one bit or as many as 24 bits and uses RLE compression.

Booklet

The printed material inside the front of a jewel box that includes the cover artwork and other information on the disc. The usual booklet sizes are one, two, four, or eight pages.

Bookmark

An indication of a place in a document to which the user may return directly. A bookmark can be created by the authoring system (such as a chapter title) or be created and saved by the user.

Box

A packaging technique for CD-ROMs in which a box of lightweight cardboard, printed with product identification, is used to hold the disc and additional material for an electronic title.

Blister pack

A packaging technique for CD-ROM or diskettes in which a disc is placed in a transparent envelope that is attached to the binding of a book.

Browse

To look through a document without a predetermined goal in order to see what it might contain that would be of interest.

Bug

An error in the contents or functionality of a disc or of an electronic title; these must be fixed before the disc or title can ship.

Bug report

A report from testing or from a customer that there is an error in a program or title, sometimes called a maintenance request. These reports are used to ensure that the product is correct when shipped or is corrected when the next manufacturing run is made.

Bundling

Including more than one title in a package that is marketed as a unit.

Button

An area on the desktop which will respond to a mouse click. These are often represented by icons that represent a choice or an action. See Hot Region.

Button palette

A collection of buttons, each with a descriptive icon or other artwork, that acts as a vocabulary unit for user interaction.

Byte code

A device-independent, compressed version of a program produced by a compiler that can be interpreted on any of several platforms. The original version was probably the Pascal P-code, but byte codes are now used by Java.

Candidate RTM

A disc that is submitted as being ready to release to manufacturing, subject to final approval. See RTM.

Capacity (Data Capacity)

The amount of data that can be recorded and replicated on a CD. Normal capacity of a disc is 654.7 megabytes, which is 335350 2K sectors. This is equivalent to a music playing time of 74 minutes 30 seconds. The amount of data on a disc is controlled by several factors track pitch, speed or rotation. It is possible to record and replicate somewhat more data on the disc than the "normal" capacity and still remain within Yellow Book specifications, but some drives have trouble reading from these discs.

Cascading menus

Menus in which one or more menu items display additional menus when they are selected.

Catalog number

A number printed on the disc label that gives the publisher's catalog number for ordering or inventory.

CAV

Constant Angular Velocity. Refers to the speed of the information track with relation to the reading head (laser). Video discs, most magnetic discs, and traditional phonograph records rotate at constant angular velocity, i.e. RPM is constant so that the tracks on the outside radii move past the reading head much faster than tracks on the inside radii. See CLV.

CD-I

Compact Disc Interactive. A compact disc format in which computer data and compressed audio are interleaved on the same track. The format includes both a disc layout and an operating system, CD-RTOS, that can read the layout and play the disc contents. CD-I discs must be mastered on special proprietary systems.

CD-MO

Compact Disc Magneto-Optical. A standard for discs that can be recorded and played by magneto-optical techniques (Orange Book, Part I).

CD-Plus

A mixed-mode disc for the music industry that allows both computer data and music to be placed on a single disc.

CD-R

Compact Disc Recordable disc (Orange Book, Part II). See CD-WO.

CD-ROM

Compact Disc Read Only Memory. A compact disc format that is used to hold text, graphics, and hi-fi stereo sound. The disc is built on the same technology as the music CD, but uses different tracks for data. The music CD player cannot play CD-ROM discs, but CD-ROM players may be able to play music CD discs and have jacks for connection to an amplifier and/or earphones.

CD-ROM Mode 1

The usual mode for data-only CD-ROM (that is, discs that contain only data and applications); it has three layers of error detection and correction for computer data.

CD-ROM Mode 2

Another mode for CD-ROM use that has two layers of error detection and correction, for audio or compressed audio/video.

CD-Video

A disc format, also known as karaoke CD or the White Book standard, that allows a combination of audio and full-motion video. It uses interleaved MPEG video and audio sectors to maximize the amount of information that can be stored on the disc.

CD-WO

Compact Disc Write Once. A CD-ROM version of the WORM (Write Once Read Many) technology. For companies wishing to do in-house preparation through premastering, this format is useful for creating test discs (one off) before sending data for mastering and replication. CD-WO discs conform to ISO 9660 standards and can be played in CD-ROM drives.

Check box

A box in which a click sets a value or attribute for the program or document. These are often found in a group that allows a user to set any of a group of attributes.

Cinepak

An asymmetric codec that gives good results for compressed digital video. Cinepak was developed by SuperMac Technology, Inc., and is now a Radius product as a result of the merger of SuperMac and Radius in August 1994.

CIRC

Cross-Interleaved Reed-Solomon Code, the error detection and correction technique used by audio CDs.

Click

A pair of events, mouse-down and mouse-up, that are used to make a selection on the screen.

Clock

An object that represents time in a document and is driven from the computer system clock. This allows you to order events, such as a sequence of movie frames, to the user in real time.

Closing sequence

The sequence of screens or information that is displayed as a title is closed.

CLV

Constant Linear Velocity. Refers to the speed of the information track with relation to the reading or recording head (laser). CD tracks pass the laser head at a constant linear velocity (1.2 to 1.4 meters per second), meaning that the speed of disc rotation when reading the inner radii must be faster than when reading the outer radii. See CAV.

Codec

A system for encoding (co) and decoding (dec) information to provide compression of a file or document.

Color depth

The number of bits used to determine the color of a pixel on the screen. The more bits used for a color, the more colors are available. Eight-bit color allows you to have 256 colors, for example; 24-bit color gives you over 16 million colors.

Color lookup table

The system used in an indexed color system to define the color used for each color index. See Palette.

Compound document

An electronic document that includes more than one computer medium in an integrated presentation, frequently with a user interface that allows the user to manipulate the individual document components.

Compression ratio

The ratio of the original size of a file to the size of the compressed file. Thus a 3:1 compression ratio means that the compressed file is one-third the size of the original.

Command keys

Keystrokes that are formed on the Macintosh by pressing the command key together with another key; these keystrokes are used to allow the user to execute some commands from the keyboard instead of from a menu. See Alt Keys.

Content

All the assets of an electronic title, together with the user interface, as assembled into the final title.

Control panel

A system extension that allows the user to set parameters for system functions. See DLL and Extension.

Copyright

The legal rights to reproduce, publish, and sell an electronic title or the contents of a title.

Copyright notice

A notice in the electronic title that states the appropriate copyrights for the title and, if appropriate, for individual content items.

Credits screen

The screen of an electronic title that lists the credits for the title's development, production, and support.

Cursors

On-screen graphic items that follow the motions of the mouse or trackball. Their shapes and actions can indicate to the user the capabilities of the area where the cursor is located or can tell the user something of the status of the system.

Cyberspace

A large and rich virtual reality in which a user can experience a range of virtual worlds.

d-characters

The characters that are legal to use in file names in the ISO 9660 disc standard. These are the upper-case alphabetic characters A...Z, the digits 0...9, and the underbar character _ .

DAT

Digital Audio Tape, a digital tape format that can be used to store or communicate data, or as disk backup.

Data fork

The part of a Macintosh file that contains the data or executable code for the file. See Resource Fork.

Data transfer rate

The speed with which data can be read from a CD-ROM drive. The standard "single-speed" rate is 150 KB/sec. Double-speed drives read at 300 KB/sec, and drives are now available that read at 800 to 1,000 KB/sec, which seems to be the top speed that is supported by the physical properties of discs.

Default

The state of a document or system as it is originally set up before the user makes any changes or customizations.

Deliverable

A component of an electronic title, such as a function or an asset, or the title itself, that is to be completed and working at a specific time in the development schedule for the title.

Derived work

Generally, a work that is created by modifying or adapting a previous work; as provided in copyright law, the right to create derived works is limited to the owner of the copyright on the original work.

Designer

The person who takes the assets of an electronic title and, using an authoring system, designs the user interface and the presentation that define the overall look and feel of the title.

Desktop metaphor

The metaphor for the computer that shows the computer's resources and activities as though they were on a desk where they can be moved around and manipulated. When mounted, a CD-ROM appears as an icon on the desktop and may open a window showing its contents.

Developer

The person or group who takes the assets and design for an electronic title, adds additional assets as needed, and assembles them all into a working document using one or more authoring systems.

Dial

An interface component that displays a value, magnitude, or position of something and possibly allows the user to change that value. Scroll bars are an example of dials.

Dialog box

A box on the screen that requires a response from the user in order to control the application or document that presented the box. Dialog boxes can be modal or nonmodal; see both terms.

Digital library

A collection of material, gathered much as a traditional library would gather material, which is all in digital form and which can be accessed across the networks. Such libraries may be distributed anywhere in the world.

Digital Video Disc

A new optical disc technology that uses denser recording techniques along with layering and two-sided manufacturing to achieve very large disc capacities. Digital Video Disc readers are able to read CD-ROMs as well.

Direct manipulation

A user interface style in which the user first picks the object, then indicates what is to be done with it; e.g., first selects a file, then drags the file icon to another disc icon to indicate that the file is to be copied to the other disc. This is a "subject-verb" kind of command, as opposed to a "verb-subject" command style such as "COPY MYFILE.DAT C:\DATA"

Directory

The list of all the files on a computer medium.

Directory path

The full sequence of directory names needed to specify a file relative to the medium on which it resides. For example, this chapter's data file on one of the authors' discs has the directory path BigDisk/EPBook/Chapters/Glossary .

Disc real estate

Disc storage, so called because there is a limited amount of storage available on the disc, and it must be developed carefully to get the most value from the resource.

Distributor

The person who takes an electronic title and sees that it is placed in retail stores and other places where it can be noticed by the potential audience.

DLL

A small piece of software that adds functionality to the Windows operating system or to an application. See Control panel.

Documentation

Information for the user of a disc, often provided on the disc's printed pieces or in the disc's contents. This often includes fundamental program operating instructions or information on required configurations for computers to use the disc.

Drag

An action sequence of a mouse-down to select an object, moving the mouse while holding the button to indicate that the object should follow the mouse, and a mouse-up to indicate an ending position, used to move a graphical object on the screen.

Drop

An ending behavior for a drag, in which the final position of the drag is on an icon for an action; this indicates that the action should be taken on the object of the drag.

DTD

Document Type Descriptor, a detailed description of the way each tag in an SGML document affects the formatting of the text covered by the tag.

Dual-directory disc

A disc with both HFS and ISO 9660 directories that may share the same files. See hybrid disc.

DVD

The acronym for Digital Video Disc; see that entry.

ECC

Error Correcting Code. A code construction that facilitates reconstruction of part or all of a message received with errors. The error correction scheme for compact discs is the same CIRC that is used for music compact discs. See CIRC.

EDC

Error Detecting Code. A code construction that makes it possible to detect when a message is received with errors.

EFM

Eight-to-Fourteen Modulation. The operation of converting 8 bits of data to 14 bits for storage on the disc, to facilitate reading data from the disc.

Electroforming

A means of creating a metal master (father) disc by electroplating nickel onto the glass master until a sheet of nickel has been built up to a usable thickness. The father can then be used in the same system to create a mother, and from the mother, stampers or metal parts are made that are used in the injection molding machine to manufacture the CD.

Encapsulation

Protecting data by only allowing access to the data through a fixed set of operations whose action on the data is limited. One of the key advantages of object-oriented programming languages is that their objects encapsulate their data.

EPS

Encapsulated PostScript. A file format for importing and exporting PostScript language files in a variety of heterogeneous environments. EPS files use a subset of the full PostScript language and may include a screen preview.

Error concealment

Techniques for recovery from disc data error with minimal notice by the user. For example, in music CDs errors are concealed by interpolating linearly between good data values.

Event

A logical entity created by a hardware condition, such as a keystroke or mouse action, or by a software action. Events are asynchronous, that is, an event may happen at any time, and a program or title must respond to each event and perform an appropriate action for each.

Event handling

Responding to an event by passing the event entity to the appropriate part of a program so it may be processed correctly.

Event queue

The collection of events that have been generated but have not yet been handled, managed as a FIFO (first-in, first-out) queue.

Extension

A small piece of software that adds functionality to the Macintosh operating system. See Control panel.

Fair use

Generally, the personal, noncommercial, limited use of copyrighted factual material in a way that does not damage its market potential, as provided by copyright law in the United States and many other countries.

FAQ

Frequently Asked Questions, a posting on an Internet newsgroup that is intended to orient a user to the issues in the newsgroup and to provide fundamental background information for the reader.

Father

The first electroformed part made from a glass master. See metal master.

Field

A distinct portion of a screen where a certain set of information, such as an image or a piece of text, will be displayed for the user.

File

A collection of information, either program or data, stored on a computer's secondary storage systems such as disk or CD-ROM.

File header

Information at the beginning of a file that describes the content of the remainder of the file. This is fairly common in image files, where the file header can describe the dimensions, color depth, and palette of the image.

File server

A computer whose primary function is to manage files and provide them for other systems on a network.

Filter

A piece of software that modifies data as it is input to a program or as it moves from one stage of a program to another.

Find

To be able to move to the point in an electronic document where a user-specified item is located; this is usually a word or phrase, but it could be another kind of content.

Firewall

A facility that screens network access to a site to protect the site's contents from undesirable access.

FOB

Freight on board, a term indicating the point from which the customer is required to pay shipping.

Font

A typeface for displaying text on the screen or for printing text on the screen.

Frame rate

The number of frames of a (digital) movie displayed per second.

FTP

File Transfer Protocol, a network technology for transferring files on the Internet.

Full color

A computer color system where each pixel holds its own RGB values, typically with 8 bits of precision for each color for a total of 24 bits per pixel. See Indexed Color.

Function

A unit of computer code that implements a specific piece of the functionality of a program.

Functionality

A behavior or activity in an electronic title such as playing a digital movie, allowing keyword searches, having hypertext links, or being able to print the document.

Ghost site

A site on the World Wide Web that may once have been available but that no longer can be reached.

GIF

A digital image format developed by CompuServe that is widely implemented on many kinds of computers. It describes images that use lookup tables of up to 8 bit depth.

Gigabyte (GB)

Roughly a billion, or thousand million, (actually 1,073,741,824) bytes, used as a measure of the capacity of a computer's disk system or of a medium.

Glass master

The medium on which manufacturers record data as the first step leading to the replication process. Consists of a glass disc larger than replicated discs, coated with a photosensitive material in which the data are recorded by a laser beam recorder (laser light).

Gold master

The completed electronic title ready for release to manufacturing (RTM) or candidate RTM. The name reflects the fact that this release is usually done on a CD-WO disc, and these discs are gold-colored. See RTM.

Green Book standard

The standard for Digital Video Discs.

Handler

The components of a program that respond to events that are passed to them by the main event loop.

HDTV

High-definition television, an emerging standard for commercial television that is expected to have a large impact on computing and electronic publishing.

Hierarchical menus

Menus in which one or more menu items, when chosen, provide a submenu offering additional choices. See Tree-Structured Menus.

High Sierra standard

The first draft proposal submitted to the International Standards Organization for common file structure for CD-ROM. When it became adopted, it was changed in minor ways and became known as ISO 9660.

Highlighting

Indicating a selection or possible selection by changing the color or presentation of the selected object to indicate that the user has chosen or could choose the object.

History

A record of the sequence of actions taken by the user in working with an electronic title, often used to allow the user to retrace steps or move to anything that was previously seen.

HFS

Hierarchical file system; the file system used by the Apple Macintosh system.

Home page

The hypermedia document that is first loaded when you start a World Wide Web browser, or the page that an individual creates to represent his or her presence on the World Wide Web.

Home screen

The main screen of an electronic title from which the significant sections of the title can be reached and to which the user should always be able to return with a single action.

Hot region

A region of the screen that can respond to a mouse event. See Button.

Hot text

A piece of text on the screen that can respond to a mouse event.

HTML

HyperText Markup Language, an SGML document type that is generally used as the authoring language for creating documents on the World Wide Web. This language allows a document author to apply appropriate text styles and to create links to hypermedia components or to additional documents by interpreting URLs.

HTTP

HyperText Transfer Protocol, an Internet document transfer protocol that is becoming the dominant protocol for sharing documents across networks based on URI references.

Huffman coding

A way of encoding data in variable-length symbols so that data that occurs more frequently is represented by shorter symbols.

Hybrid disc

A disc that contains data in both HFS and ISO 9660 directories. This can be done by having separate data for each directory or by having the two directories share part or all of the data. This latter is also called a dual-directory disc.

Hypermedia

An extension of the concept of hypertext, in which the user chooses the sequence in which to view not only the text but also the other media components of the document. See Hypertext.

Hypertext

Text in which some words are hot text that provide links to other text in the same or in a different document, allowing the reader to choose the sequence in which the text will be read as he or she is reading.

Icon

A graphical representation of a system component such as a document, disc, or application.

Idle

The state of a program when it is waiting for the next user input and is neither processing a piece of a document nor processing an event.

Image

In CD-ROM, the data assembled in the exact form wanted on the replicated CDs, i.e., completely premastered or image ready. In graphics, a picture to be displayed on the computer screen.

Indemnification

To promise to secure another from penalties or liabilities resulting from one's actions.

Indeo

A digital video codec developed by Intel that is primarily used for Video for Windows, although it is also available for QuickTime.

Indeo Video Interactive

A wavelet-based video codec developed by Intel.

Indexed color

Color that is specified by giving a color index for each pixel instead of giving the actual color components of the pixel. The color index is used to specify a color from a color lookup table where the actual colors are maintained. See Full Color.

Inheritance

Obtaining properties and functionality for an object by building your own object on existing classes or objects.

Injection molding

A process for replication of CDs wherein molten plastic is injected into the cavity of a mold under pressure, cooled and removed as a solid, clear plastic disc. The data information is transferred to the plastic in this process from the "stamper."

Installer

A tool which examines the host system to determine what software the system needs to properly execute a disc title, and then installs that software along with any application software needed to run the title.

Intellectual property

Generally, the property created when an author creates an original work; protecting the author's rights in this property is the purpose of copyright law and a copyright transfer gives the rights in this property to the copyright transferee.

Interframe compression

Compression of digital movies that takes advantage of frame-to-frame coherence to provide information for a given frame in terms of other frames that precede or succeed it.

Internet

An interconnected set of networks around the world that allows computers attached to any of these networks to exchange data communications freely. One of the chief functions of the Internet is to tie together these separate networks' diverse set of underlying technologies.

Interrupt

An action that stops a computer process. In interactive computing, interrupts may be caused by events. After the interrupt has been handled, the process may or may not resume.

Intranet

A network operating entirely within an organization such as a business, allowing persons in that organization to work with network tools without exposing their work to outside access.

IP address

A number, composed of four octets (eight-bit numbers), that identifies any computer on the Internet. This is being expanded to six octets as the number of computers on the Internet grows.

ISO 13490

A file format standard for CD-ROM and DVD discs that extends ISO 9660 and corrects many of its shortcomings.

ISO 9660

A widely used file format for CD-ROM. The ISO 9660 (formerly High Sierra) standard defines a directory structure that has been accepted by the International Standards Organization. This standard allows a CD-ROM disc to be read like a write-protected hard disk. Formatting a CD-ROM to this standard will allow CD-ROM interchange on any platform that supports the standard.

Item

An entry in a list, usually one that can be used to make a menu choice or to link to another place in the document.

IVI

The acronym for Indeo Video Interactive; see that entry.

Java

An object-oriented programming language from Sun Microsystems, somewhat similar to C++, that provides the capability of creating applets for network use.

Jewel box

The thin, clear plastic box in which audio CDs are usually sold and in which many CD-ROMs are distributed. Besides the usual jewel box, there are thinner jewel boxes as well as double-disc jewel boxes.

JPEG

A standard for encoding digital images using discrete cosine transformations and entropy coding. This standard can achieve part of its efficiency by data quantization, so it is usually a lossy encoding technique.

Keystroke

An event caused by the user pressing a key on the computer keyboard.

Keystroke combination

An event caused by the user pressing certain combinations of keys simultaneously on the computer keyboard, frequently used to extend the character set of the keyboard or to distinguish ordinary text keystrokes from command keystrokes.

Kilobyte (KB)

Roughly a thousand (actually 1024) bytes, used as a measure of the size of a file or the capacity of a computer's memory or of a medium.

Label

The printed area on a disc; also a brand label or imprint from a publisher.

Land (Lands)

The space between the pits on a CD disc where the photoresist on the glass master was not exposed to laser light. This space is more reflective than a pit. See Pit.

Launcher

A very small application whose purpose is to start up another program.

Laser

A device that creates a beam of coherent light. In a CD-ROM setting, this beam of light is reflected off the disc and the resulting reflection is measured to detect pits and lands on the disc.

LaTeX

A version of the TeX document formatting system developed by Leslie Lamport (hence the "La") and widely used in preparing technical documents. See TeX.

Lead in

On a CD, the area at the beginning of a disc where the Table of Contents (TOC) is recorded.

Link

A button whose function is to move the user to a different place in an electronic title.

Listener window

The window that gets the results of an event.

Load

To move a document from external memory, such as a CD-ROM, into the computer's main memory so it may be used.

Localization

Adapting the text of a program or title to a language other than the one in which the original was developed so it may be sold in additional markets.

Lossless

A technique for storing or compressing files that maintains all the information in the original file.

Lossy

A technique for storing or compressing files that does not maintain all the information in the original file. Typically, lossy techniques for video or images focus on removing information that is not perceived by the viewer. This kind of technique can be used for images or movies when it is deemed that the user will have an adequate result without needing all the original information.

LZW

Lempel-Ziv-Welch coding, a dictionary-based coding technique that encodes variable-length data in a constant-length code word. The dictionary is not transmitted but is reconstructed from the data that is received. This technique is patented by Unisys and commercial applications that use it must do so under license from them.

Main event loop

The logical structure of any program that operates primarily by receiving and responding to events. The basic structure of a main event loop usually looks something like this:

	Repeat
		{ receive event;
		  process event; }
	until ProgramExit.

Main menu

The "top" menu from which all the contents of an electronic title may be reached.

Manual

A printed (or less often, electronic) set of instructions on how to use a program, title, or piece of equipment.

Manufacturing

The process of creating the physical discs from the gold master, consisting of creating the glass master, making stampers, molding the polycarbonate discs, electroplating the discs, printing the labels, and packaging the discs for the customer.

Master

(verb) In compact disc manufacturing, the recording of the original media (glass) in preparation for making replicates (copies). (noun) In CD-ROM, the final recording of the desired CD-ROM image to be used as a source for mastering; this may be on tape, magnetic disc, optical disc (M-O or W-O), etc.

Mastering

The process of encoding input data, created during premastering, to the compact disc standards and recording this information as a series of pits in a light-sensitive layer on a glass substrate.

Megabyte (MB)

Roughly a million (actually 1,048,576) bytes, used as a measure of the capacity of a computer's memory or of a medium.

Menu

A list of words that describe available actions, for which an action is selected by dragging the cursor onto one of the words and giving a mouse-up action on the word.

Menu bar

The row at the top of a screen that contains keywords for a number of pulldown menus.

Metal master

The first electroformed part from a glass master. See father.

Metalizing

A process by which a thin metal coat (usually aluminum) is deposited on the clear plastic disc after it has been injection molded. The usual process is by sputtering, although vacuum vapor deposition or wet silvering can be used.

Microdollars

Very small amounts, often less than standard currency amounts, which may be charged for accessing documents online or through digital libraries. With enough uses, these amounts build up so that actual charges can be made.

MIDI

A standard for representing and communicating instructions for a music synthesizer that can be used for including music in an electronic document.

Modal dialog

A dialog box that will stay on the screen and block out all other user activity until the user responds to it.

Modem

A device that connects a computer to a telephone line and allows the computer to communicate with other computers.

Moiré

An unintended visible effect in an image caused by aliasing or bitmap scaling errors.

Mosaic

An application developed at the National Center for Supercomputing Applications (NCSA) that supports viewing hypertext documents, both locally and on the World Wide Web, with embedded graphics, sound, and movies. Mosaic was the first successful Web browser.

Mother

A metal part electroformed from the father, used for making stampers.

Mouse

A device, having both positioning and clicking functions, manipulated by the user's hand to move a cursor and make selections from screen presentations.

Mouse-down

An event that takes place whenever the user presses the mouse button down.

Mouse-enter

An event that takes place whenever the user moves the mouse into a region that can recognize this event.

Mouse-in

An event that takes place when the mouse is polled and is within a region that can recognize this event.

Mouse-leave

An event that takes place whenever the user moves the mouse out of a region that can recognize this event.

Mouse-still-within

An event that takes place after a mouse-enter event, when the mouse is polled and is still within the region in question.

Mouse-up

An event that takes place whenever the user releases the mouse button after it has been pressed down.

MPEG

A standard for encoding digital movies that includes some original frames, prediction of intermediate frames from the original frames, and interpolation of additional frames between predicted and original frames.

Multisession disc

A disc format for CD-WO discs that allows a user to write beyond the section already written.

Navigable movie

A QuickTime VR movie that includes frames of a single subject shot from a number of different points of view, and that gives the user the capability to select these individual points of view, thus navigating around the subject.

Navigation

The process of selecting and viewing various parts of an electronic title by using the user interface tools of the title to select the parts to be viewed.

Netscape Navigator

A very widely used Web browser that has led many advances in the HTML language.

Network

A connection among a set of computers that allows them to share data communication.

Next

The screen or other portion of an electronic document that has been defined as the default successor to the current document position.

Nonmodal dialog

A dialog box that can remain on the screen while the user chooses to do other things instead of responding immediately to the dialog box.

Notepad

A region of memory set aside by a document reader so that a user can create notes to himself or herself on the title being read.

Object

A software entity that has properties and can respond to messages and actions.

Object-oriented

Software that is constructed on the basis of loosely coupled objects that communicate by sending messages to each other.

OLE

Object Linking and Embedding, a Microsoft architecture for including components from several applications in a single electronic document and linking the components to the applications that created them. This allows the components to be manipulated by their creating application, not by the application associated with the main document. See OpenDoc.

OpenDoc

Apple's architecture for allowing live links from a document's components to applications that can manipulate the components directly. See OLE.

Opening sequence

The sequence of screens or information that is displayed as a title is opened.

Orange Book standard

The Philips/Sony standard for CD-WO and CD-MO discs, named for the color of the cover of the book in which the standard was published.

Package

The container in which a CD-ROM is stored, shipped, and sold, and which identifies the disc to the consumer.

Packet

A fixed-size sequence of few hundred bytes of data that is created when a message is sent on a network and is given identification that lets the network deliver this data along appropriate paths so the receiving computer can reassemble the larger message.

Palette

The set of colors used in an image when that image uses an indexed-color scheme; typically the palette can be adjusted to fit a particular image.

PDF

Portable Document Format, a file format developed by Adobe Systems for their Acrobat system that is becoming fairly widely used for electronic document interchange.

Pit (Pits)

Information spots on a CD (or optical disc). Pits are formed in a photosensitive layer on a glass master by exposure to laser light. Exposed material washes away in the developing process to form a pit. Pits are less reflective than lands, the space between pits. See Land.

Pixel

The smallest spot on the screen that can take on a discrete color; in an indexed color system, each pixel is associated with a color index, while in a full color system, each pixel has a full set of color information.

Pixmap

Another name for bitmap. See bitmap.

Platform

A computer system on which an electronic title can be played.

Player

The software that displays the contents of an electronic title for the user. Often this is a small application that interprets a master source file for a specific platform.

Plug-in

Software that extends the capability of an application.

Points of contact

The persons at a publisher, distributor, or wholesaler with whom an author or developer will work directly.

Pop-up menu

A menu presented on-screen by an object in response to an event.

POSIX

A set of standards for the UNIX operating system that were established to ensure portability and security.

PostScript

A standard page-description language developed by Adobe Systems that has become one of the key standards for printing and prepress technology and for document transportation.

Premastering

Preparing the digital data to send to the CD manufacturer for mastering and replication. The data is assembled as a contiguous image the way it should appear on the CD-ROM, including the file structure (such as ISO 9660). Disc manufacturers usually have hardware and software to premaster for customers, at an additional price.

Previous

The screen or other portion of an electronic document that the user visited immediately prior to reaching the current document position.

Print

To create a copy of part or all of an electronic title on paper or another hardcopy medium.

Proof disc

A CD intended to be used for testing. This usually refers to a one-off, CD-WO, or CD-R disc, but can also refer to one or more discs from a replicated group submitted for testing. Can be used as input for disc manufacturing.

Protective coating

A coating of lacquer or polymer deposited over the metal coating on a CD to protect and seal the metal layer. The most common method is spin-coating of a UV curable polymer over the surface of the metalized disc and then passing it under ultra-violet light to polymerize or cure it.

Publisher

The person or organization who funds the development of an electronic title and arranges for its marketing.

Pull-down menu

A menu that descends from the menu bar in response to a mouse-down event in one of the menu bar words, or in response to an appropriate command keystroke.

Pull-through

Sales of a title that are created when the title is associated with a larger series of publications.

Purge memory

To free memory that a program has allocated for other uses, such as cached pages, so that the program can use that memory for other functions.

Quantization

Replacing higher-accuracy data, either digital or analog, by lower-accuracy digital data. This can lead to aliasing effects and the loss of information.

QuickTime

An architecture for time-based presentation that was developed by Apple Computer. It is the basis for the QuickTime digital movie system, as well as for sound or any other time-based control. It is said that one could automate a factory based on QuickTime.

QuickTime VR

A system for creating immersive environments from photographic panoramas. It runs under QuickTime 2.0 for Macintosh and Windows. The VR stands for Virtual Reality. See Virtual reality.

Rack jobber

Someone who takes products from a wholesaler and sees that they are placed in shelf space, preferably good shelf space, in retail outlets.

Radio button

A button that is part of a button set, with the property that precisely one of the buttons in the set can be selected. These are designed to be used for choices that are mutually exclusive.

Reader

Software that displays an electronic title on the screen and that manages the user interaction in the title.

READ_ME

The name of a text file that tells a user important information about a disc, often including last-minute information that is not found in the disc's printed pieces or other documentation.

Red Book standard

The original CD standards, set by Philips and Sony, were published in a book with a red cover. These standards are the basis for later standards for other kinds of CD standards, such as those for CD-ROMs.

Registration card

A card that a purchaser of a title sends to the publisher to register himself or herself as a legal owner of that title. The registration card is often a printed piece that accompanies a CD-ROM, but it may be an online form that is filled out an printed or filled out and delivered to the publisher electronically.

Resolution

The resolution of an image is the dimension of the bitmap that represents the image.

Resource fork

The part of a Macintosh file that contains information such as icons or text that supports the file's presentation or operations. See Data Fork.

Restore

To reset all the parameters of the reader for a document to the status that was last saved by a Save instruction. See Save.

Retail

Selling an item one unit at a time to individual customers.

Revert

A synonym for Restore. See Restore.

RGB

A color model in which a color is determined by giving its red, green, and blue components. This color model is directly associated with the way a standard computer monitor creates color with a red, green, and blue color mask, so it is the most common color model for computer images.

RLE

Run-length encoding, a system for compressing data, particularly image data.

Rock Ridge standard

A standard for disc file systems and directories that is designed to allow users to maintain much of the directory information in a UNIX operating system. This goes beyond ISO 9660 to include longer file names with richer character sets, symbolic links for files, and the like.

ROI

Return on investment; the percentage of profits in relation to the total cost of a project.

Rollover

The act of moving the cursor over an active area on the screen. This may cause some sound or action to occur, indicating that the area is active and suggesting what will be done if the user clicks in the area.

Royalty

The portion of the publisher's income from a title that is passed to the title's author as payment for the author's intellectual property.

RTF

Rich Text Format, a set of conventions developed by Microsoft to include formatting information in a text document independently of the computer system or word processing system used to generate the text.

RTM (Release to Manufacturing)

To sign off on a gold master and certify that it is correct and ready to manufacture.

Save

To copy the parameters of the reader on a particular document so that a user can come back to the document with precisely the current status when the Restore instruction is given.

Schedule

A set of dates by which the individual tasks associated with a larger job are to be completed.

Screen real estate

The area of the screen, so called because there is a limited amount of screen space available, and it must be developed carefully to get the most value from the resource.

Scroll bars

Facilities in a window or field of a title that allow the user to see a larger set of information than can be displayed at once in the window or field.

SCSI (Small Computer System Interface)

A standard for connecting computers to peripheral devices such as CD-ROM players or external hard discs. This is the standard interface for peripherals on the Macintosh< and is sometimes used on other computers.

SCSI-2

A newer version of the SCSI interface that is up to 5 to 10 times as fast as the original SCSI standard.

Search

The instruction to examine the contents of an electronic title in order to find an item in the title that matches the user's request.

Search engine

online software that helps the user locate information on the Web or, more broadly, on the Internet by specifying words to be matched.

Sector

The smallest unit of a CD-ROM's file structure that may be accessed. This corresponds to 1/75 of a second of audio and contains 2352 bytes of digital data.

Selection

A user choice made by clicking on one or more objects so the user can specify what is to be done to the object. A selection must always be accompanied by highlighting the selected objects.

Set-top box

A device that processes data obtained from cable TV sources or CD-ROMs, and interacts through game-like devices to display its program output on a television screen. It may include a credit-card swipe for ordering merchandise or programming.

SGML

Standard Generalized Markup Language, a system for marking a text document based on its structure so it may be presented according to a format defined external to the document.

Shelf space

Space in a retail outlet in which products are displayed. Since retail sales are directly linked to exposure, it is very desirable to get shelf space in outlets for your product.

SKU

A unit of piece goods sold through retail channels.

Slider

A logical screen device that is used to control a value in a computer program. This may be a linear slider or may take the form of a dial.

Specifications

A description of the contents or functionality that are to be present in an electronic title.

Spin coating

Creating an even layer of photoresist on the glass master by using centrifugal force to spread the material.

Spindle

A set of finished CD-ROMs that are not packaged or wrapped, but are delivered by the manufacturer for the customer to package. This is named for the metal rod on which the discs are stacked during manufacturing.

Splash screen

The screen that shows while the title or application is loading into the computer.

Sprite

A graphic object that is movable, clickable, and that can be animated.

Stamper

A metal part electroformed from the mother. The stamper is inserted into the mold cavity to become one side of the cavity. "Stamper" is a misnomer inherited from the phonograph record industry. CDs are not stamped, but are injection molded.

Subcodes

Codes used in the CD format to hold various kinds of information, depending on the disc type.

Substrate

The main physical body of a disc, on which other coatings or layers may be added. Compact discs are made of polycarbonate plastic, coated with metal, then coated with a UV curable polymer. A label is then printed. The polycarbonate is the substrate.

SuperDisc

An early name for Digital Video Disc. See Digital Video Disc.

Synchronization

The process of ensuring that simultaneous events, such as events in the video and audio parts of a digital movie, are presented to the user simultaneously. This is one of the major tasks of digital movie playback architectures.

Tag

A notation in a text file that specifies how that text is to be treated or displayed.

Tagged text

Text that includes tags for formatting or linkage purposes, such as SGML or HTML text.

tar

An acronym for tape archive, a technology for creating archive libraries that is common on UNIX systems.

Tear-off menu

A menu that either pulls down or pops up and that can then be moved to another screen position and remains on the screen until it is dismissed.

Terabyte (TB)

Roughly a million million (actually 1.0995x1012) bytes, used as a measure of the capacity of a computer's disk system.

Term

The duration of a contract or agreement, after which time the agreement is no longer valid. Term may be defined as a certain period of time (e.g. five years), as perpetual, or until a condition occurs (e.g. the work goes out of print).

Termination

To cease executing a program.

TeX

A text formatting system invented by Donald Knuth in order to provide proper formatting for technical documents, particularly for mathematical expressions. It uses tagged text and often custom macros to interpret the tags.

TGA

A file format originally designed by Truevision to accompany their Targa graphics boards.

TIFF

Tagged Image File Format, a popular format widely used to store and transmit graphic images. The TIFF standard supports full-color images as well as lookup table images.

Title

An electronic document or publication that is identified and sold as a unit.

Title bar

The bar at the top of a window that gives the title of the window.

Title sequence

The sequence of screens or information that is displayed to identify the title.

TOC

Table of contents. This is information located in the lead-in area. The TOC contains a listing of where tracks start on the disc, as well as indications to the player as to what kind of disc it is: ROM, audio, etc.

Track

The sequence of pits that are read by the reading laser comprises a track. On a CD, a track is a spiral beginning at the inside of the disc and spiraling outward, and is about three miles long. Also, a contiguous portion of the spiral of pits and lands on a compact disc; on an audio CD each track ordinarily corresponds to a single song or piece. The tracks on a disc are identified in the disc table of contents.

Trackball

A device, having both positioning and clicking functions, manipulated by the user by moving the hand over a rolling ball to move a cursor and make selections from screen presentations. Events generated by a trackball are handled as though they were mouse events.

Track pitch

The physical distance between two rows of information pits, center to center. In CD the specification of track pitch is 1.5 to 1.7 microns. Most discs are recorded with a track pitch of 1.6 microns.

Trademark

A name indicating ownership of origin of a product that is legally reserved to the owner or creator of the product.

Tray drop-in piece

The printed piece that may be inserted in a jewel box below the plastic insert in which the disc hub holder is found. Also known as the tray insert or tray card.

Tree-structured menus

Menus for which individual menu choices have submenus. See Hierarchical Menus.

Truevision-S

A video codec developed by The Duck Co. for both AVI and QuickTime movies.

Turn

The time required for CDs to be mastered, made, and shipped, measured from the time premastered data, artwork, and other materials are in the hands of the manufacturer. Also known as the turnaround time.

Unicode

A technique for storing characters from most languages using two bytes per character.

UNIX

An operating system widely used for workstations. There are many variations on this operating system, depending on individual vendors, but they all function in much the same way. See POSIX.

Up

An instruction, often attached to a button, to return to the next higher level of menu or screen in a title.

UPC

Universal Product Code, the bar code that is placed on a product so it may be scanned by point-of-sale devices. Bookstores and other retail merchants want products to use UPCs to streamline the sales process. UPCs contain a company code and a product code, and a product manufacturer must apply for a company code.

URI

Uniform Resource Identifier, a set of conventions for identifying any file on any system accessible on the networks so that the file can be transferred to the host and the appropriate application can be called upon to display it.

URL

Uniform Resource Locator, a URI convention based on the network address of the file to be transferred.

URN

Uniform Resource Name, a URI convention intended to allow access to a document by a name instead of by location.

User interface

The components of an electronic title that enable the user to navigate through a document and to execute the functionality of the document.

Vehicle simulation

To present the user with the behavior and control of a vehicle from within an electronic document by use of an interface much like that of the actual vehicle.

Video for Windows

A Microsoft design for creating and playing digital video on the Windows computing platform.

Video game box

A special set-top box for playing video games. See set-top box.

Virtual reality

Real-time display of direct-manipulation interactive realistic computer graphics and digital sound with three-dimensional models, presented by a display technology that allows the user to have an experience of immersion in the model presented.

Virtual Reality Modeling Language

A specification for 3-dimensional models and interactivity across the networks, allowing for the creation and networked sharing of virtual worlds.

Virtual world

The synthetic model space in which a user is immersed in a virtual reality environment.

Volume descriptor

An area at the beginning of a CD-ROM reserved for the recording of information about the origination, originator, copyright, etc.

Volume name

The name of a file volume, such as a CD-ROM, that is mounted on a system.

Volume table of contents (VTOC)

The list of tracks, along with their position and duration, on a CD-ROM; the list of all files in the volume (the directory) on a magnetic disc.

VRML

The acronym for Virtual Reality Modeling Language; see that entry.

WAV

A digital audio format for Microsoft Windows.

Web browser

Software that allows a user to access and view documents across the computer networks and supports hypertext links through the HTML language.

Web, the

See World-Wide Web.

White Book standard

A standard developed by Philips and JVC for compact discs that supports a combination of audio and full-motion video. The video is based on MPEG video and audio that are interleaved to achieve the proper data flow rates. The standard is published in a book with a white cover.

Wholesale

Selling a product to an individual or organization that will redistribute it to individuals through one of several possible distribution channels including direct mail, catalogs, or retail outlets.

W-O

Write Once. Recordable optical disc. Can be recorded on, but not changed or erased. See WORM.

Work for Hire

Creating a piece of work under contract to another, with the rights to that work going to the person who hired the creator. This is a legal relationship that needs to be defined by a contract between the creator and the person hiring her or him.

World-Wide Web (WWW)

A system developed at the European Particle Physics Laboratory (CERN) in Switzerland for creating and browsing distributed hypertext documents.

WORM

Write Once, Read Many. See W-O

XCMD

External command, a small piece of software that extends the functionality of an application.

Yellow Book standard

When the CD-ROM standards were set by Philips and Sony, they were published in a book with a yellow cover. Thus the standard for CD-ROM is sometimes called the yellow book standard.

YIQ

A color model defined for NTSC color television that takes luminance (Y) as its primary component and uses two other components, a range from orange to cyan and a range from magenta to green, to carry chrominance information. It is relatively easy to convert back and forth between YIQ and the RGB color model that is most commonly used in computing.