Science Teaching Series

Internet Resources

I. Developing Scientific Literacy

II. Developing Scientific Reasoning

III. Developing Scientific Understanding

IV. Developing Scientific Problem Solving

V. Developing Scientific Research Skills

VI. Resources for Teaching Science





"Audio Interchange File Format," created by Apple as a standard file format for saving sound files of any type.

Audio Sectors

Audio sectors are made up of the sound data you hear plus error correction data. Audio sectors cannot be read with a standard CDROM drive. Many CD-ROM drives do, however, offer the ability to convert audio data to computer data. (see previous section "About CDs").

Audio Tracks

Audio tracks are simply a collection of audio sectors. These tracks are playable on standard audio-CD-players. For the audio-CD players to be able to recognize and play the tracks, the tracks must always be in the FIRST session on the CD.

Blue Book

The Blue Book specifies the CD EXTRA standard for interactive CDs. A CD EXTRA (also known as Enhanced CD) is a multisession CD which contains audio tracks in its first session followed by a data track in the second session.


A CD (Compact Disc) consists of up to approx. 333,000 sectors.

CD Extra - see Enhanced Music CD


CD-i (Compact Disc Interactive) is a computer system developed by Philips. It is able to read discs in the following formats: CD-i, Video CD and Photo CD. A disc in CD-i format consists of one CD-i track with mode 2 sectors (types 4 and 5, see previous section "About CDs"). A CD-i is specified in the "Green Book". Opposed to other CD-ROM XA discs, a CD-i track has no entry in the TOC.

CD-Recordable (CD-R)

CD recordables are special compact discs that can record data by using a special laser that "bums" microscopic holes in the recording layer. These pits can then be read by standard CD readers. Recordable CDs are somewhat more fragile than standard CDs, so care should be taken in their storage and handling. The label side is particularly delicate.

CD-ROM Tracks

CD-ROM tracks are made up of model sectors (type 2, see previous section "About CDs") and are used for many file systems such as HFS, ISO 9660, and others.

Enhanced Music CD / CD Extra

CD Extra is the new standard for interactive albums defined in the Blue Book. These discs consist of two sessions. The first session consists of pure audio tracks, the second session consists of a data track in a restricted format. If a CD Extra is inserted into an audio CD player only the audio tracks are visible; the data session cannot be played.

Not all discs containing an audio session and an additional data session are CD Extras! The data tracks must contain special information such as MPEG still pictures, etc. Special software is needed to create a CD Extra file structure or a QuAC file.

Green Book

The Green Book describes the details of the CD-i format (Compact Disc Interactive).


Hierarchical File System. HFS is the standard Macintosh file system. Because of the Mac's ability to use long file names and the unique data fork/resource fork structure of Mac files, HFS is not conformant to ISO Standard. On a CD recorded in HFS format, each session is represented as a separate volume on the desktop.

Both "Mac Files & Folders" and "Mac Volume" formats create CDs in the HFS format.

Index / Index-Point

Every sector contains an index which is a number between 0 and 99. Index 0 and 1 have special meanings: 0 indicates a pause sector and 1 the beginning of the data in a track.


ISO 9660 format is a standard for cross-platform CD-ROMs. Discs created in this format can be read by many different operating systems, including Mac, Windows, DOS, UNIX, etc.

However, since ISO 9660 does not support long file names, custom icons or saved directory settings (that is, "view by Icon"), it is less than ideal for discs intended only for Macintosh users.


The ISRC-Code holds the "serial number" of each track in a standardized format (as prescribed by the Red Book). ISRC codes cannot be set in Toast, Adaptec Jam has to be used to define these codes.

Media Catalog Number

The Media Catalog Number (MCN) is a unique identification number for the CD (UPC/EAN Bar-Code). It is issued centrally by the EAN authority and consists of a series of 13 consecutive digits. The MCN can be defined only in Adaptec Jam.

Mixed Mode CD

A mixed mode CD consists of one data track and several audio tracks. Data and audio are written in one session. The data track is always placed before the audio tracks on the disc and this order cannot be changed. The Mixed Mode format has generally been superseded by the audio/data Multisession format, where the first session consists of audio tracks and the second session consists of data (CD Extra or second session in HFS, ISO 9660 XA, Mac/ISO Hybrid XA format).


MPEG is a standardized compression method for audio and video data. Because of its very high compression rates, MPEG makes it possible to play full screen/full motion video from a CD. MPEG tracks consist entirely of mode2 form2 sectors and are mostly found on Video CDs and CD-i discs.


A multisession CD consists of multiple sessions, each recorded at a different time. Each of the sessions are linked together in such a way that only one logical device appears when the CD is mounted. Not all CD-recorders can record this type of CD and not all CD-ROM drives can read them.


A multivolume CD consists of multiple sessions, each recorded at a different time. Each of the sessions are completely independent of one another so that when the CD is mounted, each session appears as an individual logical volume. Not all CDrecorders can record this type of CD and not all CD-ROM drives can read them. NOTE: HFS CDs can only be multivolume, not multisession.

Red Book

The Red Book is the original CD-DA (Compact Disc Digital Audio) standard developed by Sony and Philips. The Red Book defines the format in which an audio CD must be recorded so that an audio CDplayer can play it. It also specifies what a CD-player must do to play audio CDs correctly A CD recorded in accordance with the Red Book standard can be played in any CD-player.

Run-Out Sectors

Run-out sectors are created because the write laser beam cannot be turned off immediately upon termination of data recording. Consequently, 2 sectors are allocated to be "wasted" as the laser shuts down.


The track is the smallest logical unit on a CD. A track is a minimum of 600 sectors in length and a CD can contain up to 99 tracks. There are three types of tracks: audio tracks, CD-ROM tracks and XA/CDi tracks. Each track must be preceded by 150 empty sectors.

A CD recorded in disc-at-once mode requires only the 150 sectors before track 1.

Video CD

VIDEO CD format is used to record full-motion video or movies on a CD. Playing a Video CD requires special equipment, including an MPEG decoding system.

The White Book describes the data format of a Video CD.