3" CD Cover Song PAL
33 1/3 RPM Deleted Picture Sleeve (PS)
45 RPM Demo Picture Vinyl
5" CD Die Cut Promotional Release (Promo)
5" DVD Digipack Promotional Video
7" Vinyl Digi. Compact Cass (DCC) Region (DVD)
10" Vinyl Digital Video Disc (DVD) Regular Jewel Case
12" Vinyl Double Jewel Case Remix
Acetate Eight (8) Track Cassette SECAM
A Side Electronic Press Kit (EPK) Shaped Vinyl
Barcode EP Single
Bootleg Fan Club Slimline Jewel Case
B Side Gatefold Slimline Double Case
Callout Hook Hard Shell Case Slipcase
Cardboard Sleeve Label Soundtrack
Cassette Jewel Case Snap Pack
Catalog Number Laser Disc (LD) Spine
CDR (Recordable CD) Liner Test Pressing
CD-Video (CDV) Longbox Tribute Album
Chart Position Matrix Number UPC
Collaboration NTSC Videocassette
Coloured Vinyl OBI Strip Video CD
Compact Disc (CD) One Sided Pressing Vinyl Recording
Compilation Package VHS

3" CD :  A compact disc which is 3" in diameter. Initially marketed throughout various regions around the world, it is now mostly produced only in Japan.  A large number of early CD singles were made in this format.  Some came with a plastic adaptor to allow for use in 5" CD players, but most players today contain a recessed ring which will allow for 3" CDs to played in your normal system. [top]

33 1/3 RPM: This is a vinyl recording which is recorded in such a manner that the vinyl has to be played back at 33.3 rotations per minute for the material recorded within to sound correct.  Playing the recording back at a different speed results in a distorted sound which plays too fast or too slow. [top]

45 RPM: This is a vinyl recording which is recorded in such a manner that the vinyl has to be played back at 45 rotations per minute for the material recorded within to sound correct.  Playing the recording back at a different speed results in a distorted sound which plays too fast or too slow. [top]

5" CD: The diameter is 5" on these compact discs.  These are the more common version of a compact disc.  A 5" CD can hold up to 74 or 80 minutes of music. [top]

5" DVD:  DVD stands for digital video disc, and is a format which has become very common in the last 10 years.  A DVD system uses a slightly different laser system than a CD system, allowing for information to be packed more densely on the disc.  It is a format which typically holds video, but can also hold audio as well.  [top]

7" Vinyl: A vinyl recording which is seven inches in diameter.  Most commonly used for singles.  Typically can only hold one to two songs on each side. [top]

10" Vinyl: A vinyl recording which is 10" in diameter.  These are very uncommon, and U2 have only used this format for one promotional release. [top]

12" Vinyl: A vinyl recording which is 12" in diameter.  This is the format most commonly used for vinyl, and has room to hold multiple songs. [top]

Acetate: When a record is made, making the acetate is the second point in the process (the first being a master tape recording). An acetate is a piece of metal, covered in a layer of acetone (therefore causing it to be heavier than a standard record). To make a record, an engineer places a blank acetate on a cutting lathe. The cutting lathe then proceeds to carve a groove into the acetate, based on the sound waves the acetate cutter is receiving from the sound source attached to it (a master tape). When finished, the acetate is then used to press real vinyl records. This is achieved by first coating the acetate with a layer of metal. This "metal mother" is then taken off the acetate (both 'a' and 'b' sides), and placed on a vinyl stamper (the machine that actually makers the record). These two metal mothers are then placed on the top and bottom of the machine. A "puck" (a lump of vinyl) is then placed on the vinyl stamper, with paper labels on top and bottom sides. When the vinyl stamper is activated, the metal mothers come down on both sides of the puck, squeezing the vinyl out to the edges. This is how a record is made. Sometimes, acetates contain versions of songs that are not released. Also, for every record pressed, an acetate exists. An acetate label is usually the label of the manufacturer (not the record label, but the pressing plant used, like Sterling Sound, Townhouse or Future Disc, for example). The label is usually either hand written, or is typed. [top]

A-Side: The title track to a single. The name comes from the days when singles were pressed on vinyl and had two sides. [top]

Barcode: See UPC

Bootleg: A bootleg is an unofficial release of something done by a band. The most common type of bootlegging is when fans go to a concert and secretly tape the performance for personal use. Bootlegs are not released by the record label for which the band is signed to, and are usually done without the permission of the artist.  In U2's case there have been bootlegs made of officially released items, for example each album has been bootlegged in the format of a picture vinyl disc.  None of these are official with the exception of certain versions of the War vinyl disc.  These bootlegs of albums, promos and the like are used to target the collectors market, and in many cases are quite well done and are beautiful to behold in their own right. [top]

B-Side: Any additional songs found on singles. Most of the time b-sides are songs never before released on any albums, or remixed, live, or acoustic versions of songs. This is to drum up support for the purchase of the vinyl.  The terminology comes from the days when the additional tracks were on the second side of the vinyl single. [top]

Callout Hook (or Hook): A callout hook is a very short segment of a song (normally either 5, 10, or 20 seconds long). They are used for radio promotion.  Typically they are used in the background of radio ads to alert the listener as to which song the artist does without playing the full song.  Basically, callout hooks are just to make it simpler on DJ's so that they don't have to search for a climatic part in a song, and to make the listener go, "Oh yeah! That song! I know them!". [top]

Cardboard Sleeve: Both CDs and Cassettes have sometimes been released only in a cardboard outer packaging.  These contain no plastic (like a digipack would) and they are sized in such a manner to hold the media securely.  Cardboard sleeves are easily damaged by the removal and reuse of the media within due to this tight fit. [top]


Catalog Number: Every record manufactured has an identifying number. That is the record's catalog number. This number can usually be found on the spine of the recording as well as on the media itself, and typically follows a pattern for each country of release.  Catalog numbers will vary by country for each individual release.  Some multiple media releases, like the Best of 1990 - 2000 will have individual catalog numbers for each CD within, as well as one overall catalog number on the spine for the entire package.  For example, the UK release of one version of the Elevation singles contains the catalog number CIDX780 / 588 673-2.  The Canadian version of the same single contains the catalog number 314-588 673-2 which is slightly different.  Most collectors use the catalog number to identify which releases that they possess. [top]

CD-Recordable (CDR): Technology has advanced so that CDs can be easily recorded on a simple home system.  In some cases record companies have started creating, or "burning" recordable CDs for promotional use.  These are usually produced in small numbers and are used for some of the following reasons:

a) as an advance pressing (i.e. "test pressing") for a record company executive, recording engineer or the artist, so that these individuals can hear the tracks as they have been recorded.
b) for last minute promotional items where pressing of a "silver" CD would be too time consuming such as when the Hallelujah Mix of Walk On was distributed to radio stations to promote U2's win of three Grammy awards.
c) A small "additional servicing" for radio stations after a record label has already distributed a promotional single.

CDRs almost never contain a catalog number, and because of how common CD recording equipment, they are subject to being bootlegged. [top

CD-Video (CDV): A largely obsolete but highly collectable format, briefly popular during the late 1980s. CD-Videos were produced on 5", 8" or 12" size discs and can be played on some laserdisc players. 5" CD-Video discs have the advantage of containing audio tracks which can be played on a regular CD player.  These are not in the same format as "Video CDs". [top]

Chart Position:


Coloured Vinyl: A vinyl record which is pressed in coloured vinyl instead of the more typical black vinyl. Many colours are possible as the material starts with a clear vinyl and adds a dye to bring out the colour. Due to pressing in clear vinyl with dye to add the colour these are very easy to see through and appear translucent.  In some cases dye colours can be mixed between pressing separate colours resulting in a unique colour mispressing.  [top]

Compact Disc: Today, the most common format of audio release in the world.  There are variations, but most use an aluminum core to record information giving the discs a "silver" appearance on the underside.  Some companies, such as Mobile Fidelity have pressed CDs using a gold core, which is supposed to lead to a longer life for the CD. This is a digital format which uses a laser to read information on the underside of the disc, and translate it into music.  The most common diameters for a compact disc are 3" or 5". [top]

Compilation: A compilation is an album (or a sampler) made up of various artists. Bands will normally only have one or two songs on a compilation. [top]

Cover Song: A cover song is when one artist records or "covers" another artist's song.  U2 have covered Elvis Presley's "Can't Help Falling in Love".  A song written by one artist and recorded by another is not considered a cover, only when the song has been recorded and released by the inital artist themselves. [top]

Deleted: An item is termed deleted when it is no longer possible to order new stock direct from the record company.  Most singles rapidly become deleted after initial orders have been filled. [top]

Demo: Demo refers to the early recording stages of a song - these are generally not meant for release - but occasionally an artist will release some of these unfinished versions of songs. [top]

Die Cut: A sleeve with a custom cut area or hole, usually intended to reveal a picture disc, coloured vinyl disc or the label, without having to remove it from the sleeve. [top]

Digipack: A folding cardboard CD sleeve into which is glued a plastic tray that holds the disc.  These are also called by other names such as "Eco Crap" due to the problems associated with keeping these in mint condition.  Protected only by cardboard, they are easily damaged, and in many cases the glue which is used to hold the plastic tray is no longer holding things together years after release. [top]

Digital Compact Cassette (DCC): Slightly smaller than a conventional cassette. An early competitor to Minidisc which did not really gain popularity.  These are packaged to look like a traditional cassette in size, and many DCC players had the ability to play traditional cassettes as well as DCC cassettes.  DCC is a digital format, and recorded digital information that can be translated into sound on a magnetic strip of tape. [top]

Digital Video Disc (DVD): See 5" DVD.

Double Jewel Case:

Eight (8) Track Cassette:  Yes there have been U2 8 tracks.  For those who don't remember 8 tracks you are lucky.  You might want to ask your parents about these.  They were bulkier than a cassette and worked on a similar theory, magnetized tape. You however didn't have the ability to fast forward or rewind, but could instead jump to multiple points along the recording.  This format is generally extinct these days.  The U2 8-tracks which were produced were all produced by record clubs, and were not available in stores. [top]

Electronic Press Kit (EPK): This can include many items, but a basic definition is a press kit to promote some aspect of the band (i.e. the new album) which can include both traditional paper media such as release notes and  photographs, as well as some electronic media (a CD, DVD, etc.) which includes further promotional information (i.e. an interview CD with the band.) [top]

EP: EP Stands for Extended Play - meaning it has less tracks than a full length album, but more than a typical single.  The term comes from the days of vinyl when a single traditionally had one song on each side, and an album was made up of 8 - 10 songs.  An EP usually had 4-5 songs, and those songs weren't necessarily released to radio.

The U2 release "Wide Awake in America" is an example of an EP.  It collects several outtakes onto one pressing, calls them by a different name than any of the songs on the release, and is still in print today unlike most singles from that era. [top]

Fan Club: A fan club is any sort of organization that a group of fans join.  For U2, there is one official fan club, which has been run directly as an offshoot of the band.  This fan club is called "Propaganda".  Occasionally there have been releases of materials through the fan club, which are highly prized due to their limited nature.  Of course, there have also been bootlegs pressed which claim to be from the fan club.  To date, Propaganda has released two CD compilations with it's magazine, 1995's Melon, and 2000's Hasta La Vista Baby. [top]

Gatefold: A cardboard sleeve which is manufactured in such a way that it folds in the center so that a vinyl record, cd, etc, can be placed on either side of the fold.  Some are glued shut so that the media can only be placed on one side.  This type of folding packing is often used for double vinyl releases, but is sometimes used on single media releases to allow for more room for additonal graphics. [top]

Hard Shell Case: The case typically used for cassettes which typically consists of two pieces of plastic connected together which hinge open and shut.  The front piece is always clear to display artwork on the release, and the back side is either clear or opaque. [top]

Label:  In many cases in the discography the term label refers to the center of a vinyl pressing.  The center of the item does not have a groove which produces music, and is instead flat.  This center is usually decorated with information about the release.  Two types of labels exist for vinyl, one being a sticker of some sort which covers the entire center area of the disc, and the other being information which is moulded directly into the center area, and is usually painted a different colour to make the information presented within more visible.  Label can also refer to the decoration and information presented on other types of media, such as the upper side of the compact disc, and the information presented on the outer sides of cassettes.

Label also refers to the "Record Label" or the company which presses releases by the artist. U2's releases are typically pressed on the Island or Interscope "label" but there have been variations over the years. [top]

Jewel Case: A plastic case which holds compact discs and the information inserts (cover art, track listings etc) which accompany the compact disc.  There are several formats of jewel cases, which include the regular jewel case and slimline jewel cases, as well as many variations of jewel cases for multiple media releases. [top]

Laserdisc (LD): Laserdiscs are an early digital video format, which is now all but extinct.  These look very much like DVDs, and contain digital information which translates into video images.  However compression technology wasn't as fully developed when these began production, so the discs had to be quite a bit bigger to hold the information.  A laserdisc is 12" in diameter, much like a vinyl record, and were often burned to be two sided like some DVDs have been.  U2 released several videos on the laserdisc format. [top]

Liner: Liner refers to the paper inserts inserted at the front of the CD, inside the cassette case, or notes printed on the inside inserts or back cover of the vinyl record etc.  These usually contain lyrics, producer and musician credits, special thanks from the band, etc. [top

Longbox:  When vinyl was becoming a format that was disappearing, many stores had not converted storage bins over to store other more popular formats such as cassettes and both 3" and 5" CDs.  These items were smaller in size, and often could not be displayed in these display cases meant for larger vinyl items.  The longbox was created to allow for store owners to use these larger display cases to display these smaller items.  Basically they are a box, typically with album or single artwork printed on the outside, which are 12" in length.  The box opens and the CD, or cassette can be found within. [top]

Matrix Number:  There are two types of matrix numbers.  Those on CDs and those on vinyl.  On vinyl these are the numbers and letters scratched on the inside rim of the vinyl between the playing surface of the record and the label.  On a CD these are the numbers which are visible by turning over the CD.  They are burned into the CD around the center of the CD.  These are very useful for identifying different pressings of the same release, as the matrix number is often changed for each repressing. [top]

NTSC: There are three video formats popular in the world, each of which is incompatible with each other.  These are PAL, NTSC, and SECAM.  NTSC is the video format popular in North America and Asia, including Japan.  NTSC stands for National Television System Committee.  TV systems use AC current electricity for the source on information for the timing of signals.  Since AC current varies in different parts of the world, multiple TV and video formats have been developed to answer the problems caused by the differences in electricity in these countries.  NTSC generally provides a lesser picture quality than PAL, but NTSC recordings are generally incompatible with PAL systems due to these differences in electrical current, and pricey equipment is necessary to be able to play a PAL recording on an NTSC system or vice versa.[top]

OBI Strip: This is the name for a strip of paper wrapped around a release which contains additional information.  This is sometimes shrink wrapped into the package so that it cannot be easily removed until after the shrink wrap is opened and do not necessarily circle the entire item.  Other times they are just a band of paper around the item which can easily be slipped off.  These are most commonly used in non-English speaking regions to allow for information to be presented in an alternative language for consumers in those areas. [top]

One Sided Pressing: This is a vinyl release which only has music on one side of the disc.  The second side is flat with no groove, and produces no music when attempted to be played.  Typically one sided pressings are only used for promotional items, and are usually rare. [top]

Package: Package refers to the outer casing in which media is released. These come in wide varieties of shapes, sizes and function.  Most common is packaging made from plastic with paper inserts detailing information about the recording, or of printed cardboard, or a combination of the two. [top]

PAL: There are three video formats popular in the world, each of which is incompatible with each other.  These are PAL, NTSC, and SECAM. PAL is the video format popular in Europe and Australia.  PAL stands for Phase Alternating System.  TV systems use AC current electricity for the source on information for the timing of signals.  Since AC current varies in different parts of the world, multiple TV and video formats have been developed to answer the problems caused by the differences in electricity in these countries.  PAL generally provides a better picture quality, but PAL recordings are generally incompatible with NTSC systems due to these differences in electrical current, and pricey equipment is necessary to be able to play a PAL recording on an NTSC system.[top]

Picture Sleeve: Any sleeves which have artwork or text on it referring to the release within, rather than just a generic record label advertisement. [top

Picture Vinyl: A picture vinyl is a vinyl recording which is pressed in clear vinyl, but is pressed in such a way that a thin picture image is in the center between the two sides of the vinyl.  The vinyl being clear means that one can see the image in the center through the vinyl itself.  These really are quite interesting to look at as the vinyl grooves makes for an interesting effect over top of the photo. [top]

Promo / Promotional Release: Promotional releases are typically meant for radio promotion of an album or a single, and are not sold commercially in stores.  In most cases these contain differences from the commercial release that they are promoting, sometimes containing unique edits for radio play, different artwork etc.  Due to the limited quantities that they are released in, they become quite collectible quickly, and generally are most expensive when thy can be purchased than the single or album itself.

Some items such as the boxed collection sets U2 have released are not used for radio promotion, but are used in other methods of promotion such as giveaways, contest prizes etc. [top]

Promotional Video: Promotional video refers to a short video clip which accompanies a single release. Generally they are a mini movie which portrays some aspect of the song, and are accompanied by the song playing over the images.  The "videos" you see on music television programs are promotional videos. [top]

Region (DVD): There are six regions in the world for DVDs.  Discs manufactured in one region generally will not play in equipment manufactured in another region.  So discs bought in the UK will not play on US systems.  The regional coding is entirely optional, so sometimes you will come across a disc that is formatted for region 'zero' which means it should play on DVD players manufactured in all regions.  Any incompatibilities seen with region 'zero' discs are generally due to the three different video systems, PAL, NTSC and SECAM rather than problems with your DVD playing equipment.  Region 1 is used in North America.  Region 2 is used throughout Europe and much of the Middle East.  Region 3 is used by Southeast Asia including Hong Kong. Region 4 is used in most of the Southern Hemisphere including Australia, South America, Central America and even Mexico. Region 5 is used in the former Soviet Union, India and Africa. Region 6 is used for China.[top]

Regular Jewel Case: The jewel case most commonly used for albums, or releases which are packaged with a lot of printed insert material.  They are made of three pieces of plastic, a front cover, a back cover, and an insert which snaps into the back cover and actually holds the CD.  They are usually packaged with two inserts, front and back, with the back being securely held between the back cover and the insert.  In the early days of CDs the insert plastic was typically made from an opaque black or grey plastic.  Today it is common for this insert plastic to be clear so that you can see a design through the inside plastic insert. [top]

Remix: A remix is when a song is taken by the producer and reworked in some way so that it sounds different.  This can be the addition of extra instruments, rearrangement of the lyrics, or sometimes even additional vocals not contained on the original release.  In some cases a remix is so different that one will not know it started from the original song without careful listening. [top]

SECAM: There are three video formats popular in the world, each of which is incompatible with each other.  These are PAL, NTSC, and SECAM.  SECAM was developed by France to deal with differences in electrical current coming into French homes.  Although the same current as used in other European countries, the French developed their own system for video and television rather than using the PAL system. Videos recorded in SECAM format are incompatible with systems which run under the other formats, and conversion equipment is even rarer and more pricey than PAL - NTSC conversion systems.  SECAM stands for Sequential couleur avec Memoire.[top]

Shaped Vinyl: Shaped vinyl is a vinyl recording which is cut in such a manner so that it is no longer circular.  The playing surface itself remains circular, but added vinyl at the outer edges can be cut into various shapes.  The shapes have to be balanced however, so that the vinyl is evenly balanced in weight, or the vinyl will not play properly.  U2 released a shaped vinyl single for The Unforgettable Fire single.[top]

Single: A single is a song chosen for release to radio to promote an album. Most times there is also a commercially available release for that song containing a limited number of tracks, but not always. A commercially released single often has additional tracks other than the title track.  [top]

Slimline Jewel Case:  A plastic jewel case for a compact disc which is thinner than that used for full length albums.  They are made from two pieces of plastic, a front and a back, as opposed to regular jewel cases which consist of three pieces of plastic.  These jewel cases do not have room for a back insert, and the back side of the case holds the CD direct.  These are packaged with the CD face down, so that the artwork on the face of the CD can be viewed from the back of the case without opening the case.  These are slimmer than the cases used for albums, and that is where they get their name.  These have been popular in European regions for years for singles, but only recently have become more popular in North America for singles. [top]

Slim Double Jewel Case: When double CDs first came out, the cases usually consited of two regular jewel cases interconnected. These were twice the size of a regular jewel case.  More recently a jewel case has been developed which is the same size as a regular jewel case. This is a slim double jewel case. It has a two sided plastic insert which hinges open. A CD can be attached to both sides of the plastic insert. [top]

Slipcase: An outer cardboard or plastic sleeve printed with information about the release which almost completely covers the media and packaging within.  For example, in Australia, All That You Can't Leave Behind was released with an outer slipcase, which completely enclosed the CD and jewel case contained within.  Only the spine of the release was visible on either side. [top]


Snap Pack: A format common in the Japanese market for the packaging of 3" CDs.  These are similar to a digipack, but are usually made from a lightweight paper rather than a cardboard outer casing.  These are glued together in such a manner, that the inside plastic insert which holds the CD can be broken in half and one half removed.  This allows the user to wrap the paper sleeve around a smaller inside portion, and provides more compact storage for the item. [top]

Spine: The narrow edge of a release's packaging which usually contains title, artist name and catalog number. [top]

Test Pressing: A recording that is pressed so that studio technicians, the artists etc. can hear what the recording does sound like before final approval of a track is given. These recordings are usually very limited in numbers, and are not intended for release of any sort, but some do make it into the collector's marketplace from time to time. [top]

Tribute Album: An album of songs by artists looking for exposure by playing famous songs of other artists, because they are often not talented enough to sell their own records.  The entire album would consist of cover songs from one band - i.e. several unknown artists will each cover a U2 song, collect the effort together and release it.

Some of the more well done tribute albums are done by more known artists coming together for a benefit or a cause and recording the work of others.  Bono has contributed to Tribute albums for Jimmie Rodgers, and Marvin Gaye as a few examples. [top]

UPC: This is a shortened form of Universal Product Code.  This is also commonly called a bar code.  This code is usually a white area of a sleeve which contains a series of bars and numbers.  These can be scanned in stores electronically to alert the store's computerized system as to what item is being bought.  Usually the numbers contained within are reflective in some manner of the catalog number of the item. [top]

Videocassette (Video):

Video CD

Vinyl Recording:


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