Barcoding-getting It Right

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Bar coding getting it rightRecommendations for best practice by GS1 UK

GS1 UK is the unrivalled UKauthority on cross sector supplychain standards.

Our standards and services for bar coding, electronic businessmessaging, data synchronisationand radio frequency technology arefounded on the global GS1 System.GS1 standards allow businesses toseize opportunities in areas such astraceability, inventory management,point of sale/use and collaborativeplanning. Over 1,000,000 companiesglobally use these standards toachieve efficiencies in theirbusiness.

GS1 UK is part of the worldwideGS1 network. We are a not-for-profitbusiness association with over18,000 UK members. GS1 UK aimsto make supply chain standards andthe adoption of related technologyaccessible and affordable for thelargest to the smallest UKcompanies.

Bar coding has transformed valuechain management over the lasttwenty years, and the ability tocapture data automatically atevery significant point in the valuechain enables faster and moreefficient management. We aremoving closer to the point whenall the trading organisations in anyvalue chain can begin to worktogether as one linked enterprise,with the scanning of productsproviding a flow of informationthat informs all other actions.

The accuracy of bar codes remainsfundamentally important becausewhen a bar code fails to scan itadds cost to the trading process.At best data has to be keyed inmanually, and at worst customersmay reject a completeconsignment of goods, resulting inlost sales and possible financialpenalties. It has been estimatedthat the cost of poor bar codequality in the UK is somewherebetween 500 million and 1billion pounds per year, and thisbooklet explains clearly how toachieve accurate bar codes thatwill scan the first time, every time.

Bar codes used in open trade must meet the requirements ofthe GS1 System which is managedglobally by GS1. In the UK theseGS1 standards are promoted andsupported by GS1 UK.

Printing a good quality bar codethat conforms to GS1 standardsmay cost more than printingunscannable symbols, but the benefits outweigh thecosts. This booklet sets outrecommendations for best practicethat will require investment inappropriate staff and equipment.

This advice is endorsed by GS1 UKwhich is responsible for ensuringthat UK users have the supportthey need in their use of the GS1System. If the application of any ofthese guidelines is unclear, pleasecontact the staff of GS1 UK forclarification. More detailedinformation about the technicalaspects of the system can beobtained from GS1 UK and byconsulting the GS1 GeneralSpecifications which are availableat the website www.gs1uk.org.

JAMES E D SPITTLE Chairman, GS1 UK

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Foreword

Foreword 1

1. Summary of main changes 4

2. What bar codes do 5

3. Number allocation 6What happens when a consumer unit is also a traded unit?Number notificationRe-using item numbers

4. The ideal bar code 8For consumer unitsFor traded unitsFor logistics units, for example palletsBar code originationBar code colours

5. Choosing the correct bar code 13

6. Bar codes on consumer units 14Main requirementsX-dimensionLight margins or quiet zones

7. Bar codes on traded units 16Using EAN-13 or UPC-A bar codes

Using ITF-14 bar codesMain requirementsBearer barsLight margin indicators

Using GS1-128 bar codesMain requirementsBearer barsLight margin indicatorsWhen are brackets required around the application identifiers?Products with a shelf life of up to 42 daysVariable measure products

8. Pallet labels 22Position of label on pallet

9. The verification process 25

10. Common problems to avoid 28

Contents

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11. Checklist 32

12. Summary of best practice recommendations 33

13. Bar code management 35

14. Glossary 36

Appendix 1 38Bar code dimensions

Appendix 2 39Creating GTINs and SSCCs

Global trade item numbersCreating GTIN-13sCreating GTIN-12sCreating branded variable measure restricted circulation numbers (RCNs)Creating own-label variable measure restricted circulation numbers (RCNs)Creating GTIN-14sComponent parts of GTIN-14Creating SSCCsCheck digit calculation

Appendix 3 44Printing techniques

Printing on demand

Appendix 4 46Printing GS1-128 bar codes

Function 1Choosing the correct character setConcatenationChoosing the correct sizeHeight of bars Keeping adequate light marginsWhen are brackets required around the application identifiers?Determining the length of a GS1-128 bar codeChoosing the correct application identifiers

Appendix 5 49Symbol show through

Appendix 6 50How x-dimensions and magnification factors compare

Further information 51

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41. Summary of main changes

The list below sets out all the majorchanges that have been madesince the IGD booklet, Bar coding recommendations for bestpractice was published inNovember 1997. Changes to theGS1 System are made in the lightof the experience of usersworldwide. GS1 UK contributeschange requests and informationon behalf of our members toensure that the standards work inthe best possible way for UKbusinesses.

Change of name ofsystem In February 2005 the name of theEAN.UCC system was changed toGS1. This has resulted in changesto the names of some technicalterms. UCC/EAN-128 bar codes arenow known as GS1-128 bar codes,but the names of all the other barcodes remain unchanged.

For all trade items Bar code numbers (global

trade item numbers or GTINs)should not be re-used until atleast four years have elapsedsince they were last used on otherproducts. For clothing, this period is reduced to 30 months. This period used to be three years.

For consumer units(retail trade items) No bar code should ever be closer

than 8 mm or further than 100mm from the edge of anypackaging or container. This is achange from being no closer than5 mm to an edge.

The light margin at the top ofEAN-8, EAN-13, UPC-E and UPC-Asymbols is no longer required.This results in a 0.33 mmreduction in height for nominalsized symbols, but does not resultin a visible change to thesesymbols. The light margins to theleft and right do not change.

For traded units (outercases or trade itemgroupings) and palletsThe following changes have beenmade as bar code scanners workmore effectively if they are readingbar codes of similar sizes. Thesenew minima and maxima reducethe variation in the size of thesebar codes.

The height of the bars of any barcode should be at least 32 mm.This is a change from 25 mm.

The size of the GS1-128 bar codehas been redefined. The width ofthe narrowest element at 100%magnification is now 1.016 mm,not 1.000 mm, and the range ofmagnifications allowed in generaldistribution is from 48.7% to100%. The previous range of sizeswas from 25% to 120%. This newrange is the same as defining the x-dimension (the width of thenarrowest bar or space) range as 0.495 mm to 1.016 mm.

The range of magnifications forthe ITF-14 symbol has beenchanged. The range is now from48.7% to 100%. The previousrange of sizes was 62.5% to 120%.This new range is equal to an x-dimension range of 0.495 mm to 1.016 mm.

When two bar codes are pre-printed onto the packaging oftraded units, they may be placedon opposite sides, if it is not possible to achieve two scannable symbols onadjacent sides.

H-gauges are now not formallypart of the GS1 GeneralSpecifications and they do notneed to be included outside the light margins of any ITF-14 symbols.

The GS1 GeneralSpecifications are updatedevery year, and the latestinformation about them is always available from theGS1 UK Helpdesk, 020 7655 9001, or via thewebsite, www.gs1uk.org.

52. What bar codes do

All bar codes represent data in a machine readable form. Thedifferent widths of bars and spacesin a bar code symbol representdifferent numbers or letters whichcan be decoded by a bar codescanner. The data is then sent back to the appropriate computersystem where it is recorded andused as a prompt for further action.

Bar codes used at the retail pointof sale represent a global tradeitem number (GTIN) which acts asa key to information held on adatabase. It is important that eachGTIN correctly identifies theproduct and that the bar coderepresenting this number caneasily be seen and scannedsuccessfully.

The bar codes used on outer cases(trade items that do not cross aretail point of sale) will sometimesrepresent a GTIN by itself. When itis also necessary to have additionalinformation such as expiry dates,batch information or serialnumbers in a machine readableform, this will also be included inthe bar code.

Logistics labels are used to identifythe units transported in the supplychain and examples include palletsof goods.

All of the bar codes in the GS1 System use the GS1 businessdata standards. These standards areagreed internationally by GS1 and are the basis for effectiveunambiguous communicationsbetween companies in valuechains and their final customers,who may be consumers at theretail point of sale.

This booklet will explain moreabout the printing and positioningof bar codes, but it is not intendedas a replacement for the GS1General Specifications (which havereplaced the Article NumberAssociations Article Numberingand Symbol Marking OperatingManual). These specifications areavailable free of charge via the GS1 UK website at www.gs1uk.organd they can be downloaded inWord format. Copies of the latestGeneral Specifications on CDROM can also be purchased from GS1 UK for 20. Contact the GS1 UK helpdesk on 020 7655 9001 for furtherinformation.

63. Number allocation

It is vitally important that eachcompany bar coding its productshas a unique company prefixnumber from GS1 UK or anotherGS1 authority. This number, whichcan vary in length, is then used asthe basis for the creation of uniqueglobal trade item numbers (GTINs)as explained in appendix 2.

Each company must ensure thatevery different product line has adifferent number. If particularlevels of packaging also need tobe identified for trading purposes,then each level being identifiedrequires a different number.

The number allocated to aconsumer unit (an item that couldbe sold at a retail point of sale)must be changed when

the declared weight is different extra product is provided free, for

example 10% extra the name of the product

changes, for example fromMarathon to Snickers

a free gift is attached to the item different prices are pre-printed

on the packaging

Numbers allocated to consumerunits must remain unaltered when

a free gift is included inside the item

a promotional offer is beingadvertised

the undeclared weight changesby an amount that does notaffect its handling within anysupply chain

a minor packaging change, for example a different type ofsimilar packaging material is now being used

Different numbers are required onouter cases (traded units or tradeitems that do not cross a retailpoint of sale) when

they contain different quantitiesof the same consumer unit

the products inside the outercase have a new item number

a promotion needs to bedistinguished for ordering andinvoicing purposes

the packaging of the consumerunits changes significantly, forexample when a glass containerreplaces a plastic container

Changes of number are requiredwhen the outer case needs to bedistinguished from any other outercase. Changes in packagingmaterial may affect the grossweight of the item even though allother aspects are unaltered. Thisweight change may affect thelogistics processes involved in theproducts handling, so a differentnumber is required.

If the product is only ever sold at a traded level, use either anEAN-13 bar code of at least 150%magnification, or an ITF-14 or GS1-128 bar code.

What happens when aconsumer unit is also atraded unit?When a product is traded betweencompanies and also sold at theretail point of sale, the product isboth a traded unit and a consumerunit. Examples are a sack ofpotatoes, a toaster or a 12-pack of canned drinks. It does not needa new number for the secondpurpose as its identity is still the same.

Number notification Poor communication of itemnumbers between trading partnersprevents effective handling oftrade information. Following goodpractice will achieve immediateimprovements, at no extra cost.

For proprietary branded productsthe manufacturer or supplier willnotify the wholesalers or retailersof the GTINs being used

For own brand products, theretailer or wholesaler will let themanufacturer know whichnumbers are to be used toidentify new products

When a new product is beingintroduced, all the GTINs that relateto it must be notified to all thetrading partners before theproducts are first supplied.

Re-using item numbersThe global trade item number(GTIN) for a product can be re-usedif it is at least four years since thenumber was last used to identifysomething else. Even if the firstproduct had a very short shelf lifethe number must not be re-usedbefore this time has elapsed or itmay cause confusion with yourtrading partners.

The only exception is for clothing,when numbers can be re-usedafter 30 months. This is becausemany of these are used to identifyfashion items that are only sold forone season.

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It is always worth checkingwhether re-using numberswill cause any problems withyour major customers beforedoing this. In the musicindustry, for example, re-using numbers may causeproblems because a re-issuedrecording may require thesame number it had 10, 20 or30 years ago.

The ideal bar code is one thatrepresents the correct data, and isscannable when printed within theallowable range of sizes. The GS1 General Specifications providea basis for determining the correctsize of a bar code and alsorecommend the use of verificationequipment which can measurehow well a bar code has beenprinted and give an indication ofhow easily it will be scanned inpractice.

The correct bar code must bechosen before including it on thepackaging of the product. Thedifferent types of product and thebar codes will now be explained.

For consumer unitsScanners at the retail point of sale are designed to read EAN-13,UPC-A, EAN-8 and UPC-E barcodes so one of these symbolsmust be used. Most UK users willuse EAN-13 bar codes on theirproducts (or EAN-8 bar codes forvery small products).

Bar codes must be in the samelocation on all similar shapedproducts

The bar code must be no closerthan 8 mm to a seam orpackaging fold

The bar code must be on a flat orconsistently curved surface

The bar codes on consumer unitsmust not be visible through theouter packaging

For small cylindrical products, thebar code must be positionedvertically (ladder orientation) tothe curve, subject to the printingprocess and or the direction ofprint

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4. The ideal bar code

The ideal bar code is one that represents thecorrect data, and is scannablewhen printed within theallowable range of sizes.

UPC-A

EAN-8

EAN-13

UPC-E

All of these bar codes are at 100% magnification.

For traded unitsScanners at goods inward and atthe wholesale point of sale aredesigned to read EAN-13, UPC-A,ITF-14 and GS1-128 bar codes, soone of these must be used. Thesymbols used on very smallproducts, the EAN-8 and UPC-E barcodes, will not generally be usedon traded units.

Traded units may be handledautomatically by goods inwardsystems and so the bar codesmust always be printed so that the bars of the symbol are uprightwhen the unit is in its normal

storage position. Traded units willoften be sold at a wholesale pointof sale, and it is very importantthat the bar codes on theconsumer units inside themcannot be scanned at these points of sale.

A minimum of one bar code isrequired, but two arerecommended when the barcodes are pre-printed direct ontothe outer packaging. This isbecause the cost of pre-printingan extra symbol is minimal, andshould one bar code becomedamaged and unreadable, the

second one should still bescannable. When two symbols areprovided, ideally one should be ona short side and the other on theadjacent long right hand side, butthey can be placed on oppositesides if these means they will bothremain scannable.

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ITF-14 bar code with x-dimension of 0.635 mm

(01)25012345678904(17)071225

The data in this bar code provides the

information that the GTIN is

25012345678904 and that the

products expiry date is

25 December 2007

GS1-128 bar code with x-dimension of 0.50 mm

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If bar coded labels are being used,then one label is sufficient. This isbecause these bar codes aregenerally of a higher quality andwill be scanned more reliably. Thislabel should ideally be placed onone long side of the item.

The bar codes on consumer unitsinside the outer case must not bescannable through the outerpackaging

The bar codes must be upright, inpicket fence orientation, so thatthe bars are vertical

The minimum height of the barsof the bar code must be 32 mm

The bar codes including theirlight margins must be no closerthan 19 mm to a vertical edge

The bar codes must not beobscured by any final packaging

For logistics units, forexample palletsScanners used to read labels onlogistics units are designed to readGS1-128 bar codes.

All the bar codes on the palletlabel must be GS1-128 bar codes.

There must be two identicallabels on each unit

One label must be placed on ashort side and the second labelmust be placed on the adjacentlong right hand side


The minimum height of the bars of all the bar codes must be 32 mm

The bar codes must be upright, inpicket fence orientation

Bar code originationBar codes can be sourced as filmmasters (positive or negativeimages as required by theproduction process), as digital EPS (encapsulated PostScript) files sent electronically, or throughthe use of bar code productionsoftware used in-house. Whichevermethod is used it is important todetermine the correct size for theparticular use of the bar code, andthen the choice of substrate andprinting technique.

More details are provided inappendix 3.

The use of verification equipmentis recommended to check thesemaster images, especially whenartwork has been created digitally.Film masters will already havebeen verified by the film mastersupplier to ensure that they havebeen accurately produced.

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It is recommended that the barcodes on the finished products are then verified to ensure that allthe production processes haveresulted in a scannable bar code.Verification equipment meetingthe requirements of ISO/IEC15426-1 must be used as it willprovide a check on all theimportant criteria.

More information aboutverification is provided in section 9.

This verification is stronglyrecommended becausewholesalers and retailers areincreasingly using automatedscanning systems at their goodsinwards and points of sale, andpoor quality, unscannable barcodes create additional cost anddelay for their operations.

Bar code coloursBar codes must be printed so thatthe darker bars appear against apaler background. It is not possibleto read a bar code if it is reversedout, that is, printed with white barsagainst a coloured background.Scanners detect the difference incontrast between the bars andspaces using red light, and it isimportant to use colours that willmaximise this contrast.

If using a semi-transparentsubstrate, do not rely on thecolour of the contents of thepackaging to provide abackground colour: print abackground in white, yellow,orange or red to provide a solidcontrast with the bars of thesymbol. Black bars on a whitebackground are a good

combination, but other coloursmay be used provided the barshave a high blue, black or greencontent and are printed on abackground that is white, yellow,orange or red. The illustrationsoverleaf show examples ofscannable and non-scannablecombinations of colour.

Verifiers that meet therequirements of the internationalspecification ISO/IEC 15426-1 areable to measure the contrast of aprinted bar code, and they mustbe used to check that particularcolour combinations arescannable.

Any colours used for the printingof the bars must be pure colours,and not printed out of theconventional four colour process.It is not always necessary tointroduce black as an extra colour to print the bars if one ofthe colours already used in thedesign will appear black under red light. Use a verifier compliantwith ISO/IEC 15426-1 to check thatthe chosen combination will workeffectively.

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Non-scannableScannable

Bar code coloursBecause scanners use red light, only certain colour combinations can be used.

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The rules set out below will helpyou choose the correct bar codefor each level of packaging.

1. If the product is a consumerunit (it could be sold at a retailpoint of sale), use an EAN-13,UPC-A, EAN-8 or UPC-E barcode to identify it.

2. If the product is a traded unit(a product that will not be soldat a retail point of sale), any ofthe GS1 bar codes may beused. If bar codes are printeddirect onto fibreboardpackaging, ITF-14 symbols may need to be used.

3. If the traded unit could also besold at a retail point of sale (forexample, a box of 24 cans ofbeer), it must be bar codedwith at least one EAN-13 orUPC-A at a magnification of atleast 150%.

4. If EAN-13 or UPC-A symbols areprinted on a traded unit, makesure that the packagingmaterials are of an adequatequality to allow for scannablesymbols to be printed. Theouter packaging of the tradedunit must also obscure all thebar codes that appear on theproducts inside it.

5. If the traded unit has a shortshelf life, say less than 42 days,use a GS1-128 bar code toencode the GTIN for the itemand its expiry date. Most userswill not be able to achieve asymbol of adequate qualityunless they use print and applylabels or use white kraft boardas the substrate.

6. If the traded unit has to be barcoded with extra information,such as a batch number orvariant number, also use a GS1-128 bar code to encodethis information together withthe GTIN.

7. If the traded unit is of variablemeasure, use a GS1-128 barcode, which will encode themeasure (often the weight inkilograms) alongside the GTIN.

8. If pallets are being labelled,only GS1-128 bar codes mustbe used on the label.

5. Choosing the correct bar code

Since 1 January 2005 EAN-13 symbols havegenerally been acceptable at retail points of sale inCanada and the USA.

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6. Bar codes on consumer units

Consumer units (items that may besold at a retail point of sale) mustbe bar coded with EAN-13, UPC-A,EAN-8 or UPC-E symbols, and theyare shown alongside. All of thesebar codes are shown here at a sizeof 100% and whenever they aremade smaller or larger they mustbe kept in proportion. The heightof the bars should not be reducedunless absolutely necessary as thisreduction reduces the bar codesscannability.

The UPC-A bar codes are theAmerican equivalent of EAN-13 barcodes and occupy the same areaas an EAN-13 bar code. They canbe used in the UK and elsewherewith no problem.

The EAN-8 bar code represents a GTIN-8 number which is directlyassigned by GS1 UK for theidentification of very small items.

The UPC-E bar code is a specialrepresentation of a GTIN-12number that would otherwise be shown in a UPC-A bar codesymbol. These bar codes can bescanned in the UK but they are notgenerally available for UK users tocreate. Further information aboutthese symbols is available in theGS1 General Specifications andfrom GS1 UK.

These four symbols EAN-13, EAN-8, UPC-A and UPC-E aresometimes referred to as EAN/UPCsymbols. The bar codes have anominal or 100% size which canbe varied, and the size chosen willdepend on the printing processbeing used and the quality of theinks and substrates being used.Appendix 1 shows these symbolsmarked up with their nominaldimensions.

UPC-A

EAN-8

EAN-13

UPC-E

All of these bar codes are at 100% magnification.

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Main requirements The bars of the codes must

not be shortened in height(truncated) unless the productssize makes this absolutelynecessary

Adequate light margins or quietzones must be provided to theleft and right of each bar code

The target size is 100% but thestandards allow a range between80% and 200%. However, keepthem in the 80% to 120%magnification range if printquality allows.

When printing bar codes smallerthan 100% remember that theprinting tolerances are muchtighter, and you must use highquality printing processes. It is notalways possible to improve thequality of the printing process sotests must be carried out beforecommitting to a particular size ofsymbol. If the consumer unit isalso a traded unit, please see thenext section for advice on the barcodes size.

X-dimensionWhen any of these bar codes is atits nominal or 100% size the widthof the narrowest bar or space is0.33 mm. This measurement is alsoknown as the x-dimension or themodule width, and this expressionmay sometimes be used to specifythe size of a bar code. The width of the other bars and spaces is two, three or four times the x-dimension.

Light margins or quiet zonesThe clear spaces to the left andright of each bar code are veryimportant as they are used by thescanner to determine where thebar code starts and finishes. Theselight margins or quiet zones mustbe the same background colour asthe rest of the bar code andnothing must be printed in theseareas except for the symbols lightmargin indicators. These lightmargin indicators are optional, butthey are strongly recommended tohelp safeguard the light margins.

The nominal dimensions for theselight margins are provided inappendix 1, but it is important toallow slightly more than this spaceat each side to allow for variationin printing tolerances.

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Traded units are sometimes calledtrade item groupings. These tradedunits may cross a wholesale pointof sale, and may also be scannedin automated goods handlingsystems. These are those itemshandled by manufacturers,distributors, wholesalers, andretailers at goods inwards. They arealso known as outer cases, andusually contain a predefinednumber of consumer units, theitems sold at a retail point of sale.

These items can be bar coded with EAN-13, UPC-A, ITF-14 orGS1-128 symbols depending on the type of outer casepackaging material being usedand the type of informationrequired by trading partners.

Some products, such as washingmachines, furniture, largemultipacks of canned drinks, areboth traded units and consumerunits. If this is the case, the itemnumber is the same for both uses.An EAN-13 or UPC-A symbol isrequired for the retail point of sale.

Using EAN-13 or UPC-Abar codesIf an EAN-13 or UPC-A bar code isprinted on the packaging of atraded unit:

The bar code must have amagnification of at least 150%, sothat the width of the narrowestbars is at least 0.495 mm

A minimum of one bar code isrequired, but two arerecommended when the barcodes are pre-printed direct ontothe outer packaging. If possible,one bar code should be on ashort side and the other on theadjacent long right hand side.

It must not be possible to scanany of the EAN or UPC bar codeson any of the items insidethrough the outer packaging. For further information seeappendix 6

The bar code must have lightmargins to the left and right, andthe use of light margin indicatorsis strongly recommended as ameans of safeguarding these

The bar code must be upright, inpicket fence orientation, so thatthe bars are vertical

The bar code including its lightmargins must be no closer than19 mm to a vertical edge

UPC-AEAN-13

Examples of EAN-13 and UPC-A bar codes printed at a magnification of 150% are shown below:

7. Bar codes on traded units

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Using ITF-14 bar codesIt may be necessary to use ITF-14symbols when bar codes are beingprinted directly on to fibreboardouter cases. If you have to provideextra variable information such asexpiry dates or batch numbers,you will have to use GS1-128 barcodes which are explained below.

Examples of an ITF-14 symbolprinted at its nominal size(equivalent to an x-dimension of1.016 mm) and at reduced sizeswith x-dimensions of 0.635 mmand 0.495 mm are shownalongside. Although the x-dimensions are smaller, theheight of the bars remains at 32 mm, as shown here. As with the EAN/UPC symbols theaim is to print a scannable barcode within the specified sizerange.

ITF-14 bar code at nominal size



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Using ITF-14 bar codesMain requirements When printing directly onto

fibreboard cases use symbolswhich have an x-dimension of1.016 mm

A minimum of one bar code isrequired, but two arerecommended when the barcodes are pre-printed direct ontothe outer packaging. If possible,one bar code should be on ashort side and the other on theadjacent long right hand side.Only one bar code is required if alabel is used or the bar code isprinted on demand

The bars must be 32 mm tall. Thisis a change from the previousrecommendation of 25 mm and has been made tohelp improve the performance ofautomated scanning systems

Clear light margins must beprovided on both sides of thesymbol

The wide to narrow ratio for thebars and spaces should be 2.5: 1.The acceptable range is from2.25:1 to 3.0:1.

The bar codes on the consumerunits inside the outer case mustnot be scannable through theouter packaging. For furtherinformation see appendix 5



The minimum acceptable size forITF-14 symbols has been reducedto an x-dimension of 0.495 mm

Only use ITF-14 symbols with an x-dimension of less than 0.635 mm when printing on tolabels, or directly on to highquality substrates; samples willneed to be checked to ensurethat these symbols are scannable

Bearer barsThe heavy box around the ITF-14symbol is called the bearer boxand it must always be includedwhen pre-printing directly on tofibreboard materials.

If the ITF-14 symbol is printedusing on demand printingequipment it is only necessary toprint the top and bottom bearerbars and these should have awidth of at least 1 mm.

These bearer bars prevent any mis-scanning of the ITF-14 symbols,and help prevent the top andbottom of the bars from splayingapart when using flexographicprinting plates. When these barcodes are printed on demand thebearer bar still prevents mis-scansand may also provide a visiblecheck that all the print headelements are working.

Light margin indicatorsLight margin indicators are notmandatory but are stronglyrecommended. Users of ITF-14symbols must be confident thatadequate light margins are beingprovided.

It is also important to check thatthe bar codes are not obscured byany final wrapping or treatment ofthe item.

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Using GS1-128 bar codesThese bar codes, together with theapplication identifier standards,enable companies to provideadditional information about aproduct alongside the GTIN for theproduct itself. These bar codescannot be scanned at the retailpoint of sale so they are restrictedto use on traded units.

These bar codes arerecommended when it isnecessary to be able to scan

Use by and best before dates Measurements for variable

measure products Batch and serial numbers

The different types of data mustbe specified by the applicationidentifiers which appear inbrackets before each data field.Remember that the brackets arenot data and must not beencoded into the symbol. Thebrackets are only shown aroundthe human readable numbersbelow each bar code. Full detailsabout the choice of applicationidentifiers are provided inappendix 4 and in the GS1 GeneralSpecifications which are availablevia the GS1 UK website.

The size of the GS1-128 bar codewill depend on the amount ofinformation it includes so

Make sure no bar code, includingits light margins, is longer than165 mm

If the bar code would be toolong, use two or more bar codesto show the information

Main requirements A minimum of one bar code is

required, but two arerecommended if these are pre-printed direct onto the outerpackaging. One bar coded labelor one on-demand printedsymbol is sufficient.

When printing on labels, theminimum and target size is an x-dimension of 0.495 mm, whichmeans the narrowest bars andspaces have a width of 0.495 mm

When printing on fibreboard, usesymbols which have an x-dimension of 1.016 mm

The minimum bar height is 32 mm. This is a change from theprevious recommendation andhas been made to help improvethe performance of automatedscanning systems



The bar codes on theconsumer units inside theouter case must not bescannable through the outerpackaging. For furtherinformation see appendix 5.

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Bearer barsThese are not mandatory but arestrongly recommended tohighlight bar code printingproblems. When GS1-128 barcodes are printed on demand inpicket fence orientation anymissing print head elements willshow up as white gaps in thebearer bars at the top of thesymbol. The use of bearer bars willhelp ensure accurate productionof these symbols.

Light margin indicatorsLight margin indicators are notmandatory but are stronglyrecommended. Users must beconfident that sufficient lightmargins are provided at each sideof the symbol. The diagram belowprovides an example of a suitableformat for these.

When are brackets requiredaround the applicationidentifiers?Brackets are used around eachapplication identifier (AI) when thedata is printed below the bar code.This makes it easier for people toread the AI and the data it defines.The brackets must not be encodedinto the GS1-128 symbol itself.

Products with a shelf life of up to42 daysIn the UK most retailers expectshelf life dates to be bar coded onproducts whose shelf life is lessthan 42 days.

An example of a bar code for ashort life product is shown below.

The AI 01 defines the GTIN for theproduct while the AI 17 definesthe expiry date in the formatYYMMDD. If a best before date isrequired, the AI 15 is used.

The data in this bar code provides

the information that the GTIN is

25012345678904 and that the

products expiry date is

25 December 2007.

(01)25012345678904(17)071225

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The GS1-128 bar code has lightmargins to the left and right whichare also indicated by the optionallight margin indicators. If the barcode is printed in picket fenceorientation, the horizontal bearerbar in this example will also makeit easier to see if any of the printhead elements are not working. If the code is printed in ladderorientation, any missing print head elements will show up ashorizontal white lines across thesymbol which will reduce itsscannability. This is because thewhite lines will divide the symbolhorizontally and make itunreadable by some scanners.

For further information about ondemand printing, see appendix 3.

Variable measure productsWhen traded units contain catchweight items (items that do nothave a predefined weight), thenthe net weight of the contentsmust be shown in a GS1-128 barcode. Other variable measuressuch as length, area and volumecan be shown using differentapplication identifiers, but weightis the most common measureused in the UK. For further detailsabout the other applicationidentifiers, see chapters 3 and 4 of the GS1 General Specifications.

Use the AI 3102 to give the netweight in kilograms to twodecimal places. Other AIs can be used to give weight to adifferent number of decimalplaces

The GTIN must be a 14 digitnumber beginning with 9

The data in this bar code provides

the information that the GTIN is

95012345678903, that the products

net weight is 12.75 kilograms, and

that the expiry date is 25 December

2007.

(01)95012345678903(3102)001275(17)071225

NOTE Some softwarepackages for bar codeproduction have not beenupdated to reflect the GS1General Specifications whichwere introduced in January2000. These altered theallowable sizes of both ITF-14and GS1-128 bar codes. Thesesoftware packages may stillallow for the printing of thesebar codes at sizes that arenow outside the specifications.

Please consult softwaresuppliers for possibleupdates.

22

Pallets and other transport unitsmust be labelled with a GS1logistics label and an example ofone is given opposite.

For further information aboutusing pallet labels, see theharmonised European guidelinesavailable via the GS1 UK website,www.gs1uk.org.

The x-dimension for the GS1-128bar codes shown here is 0.495 mm, and this is both theminimum and target size thatshould be used.

The GS1 General Specificationsstipulate that GS1-128 bar codesmust be used on these labels torepresent the GS1 defined data.

The most common label size isclose to A5 which is 148 mm wideand 210 mm tall. If lessinformation is required, somecompanies will choose to use alabel size close to A6 which is 105 mm wide and 148 mm tall.The actual size of the label willdepend on the requirements ofthe particular value chain, and anysize of label may be used.

The label uses GS1-128 bar codesand provides information that willbe useful to all the participants inthe transport and distributionchain.

Each shipping container,transport unit or pallet isidentified with a unique trackingnumber called a serial shippingcontainer code or SSCC

The SSCC is an 18 digit numberthat is unique for each unit

The SSCC is specified by the AI 00

The bar code containing theSSCC must always be the lowestbar code on the label

In addition to the SSCC most userswill provide details of the contentsof the pallet.

Use AI 02 to give the GTIN of the cases on the pallet togetherwith AI 37 to provide a count ofthe cases

Only use AI 01 to give a GTIN forthe pallet, if the pallet has a pre-defined configuration, and it is atraded unit. AI 01 must not beused together with AIs 02 and 37

Use whichever extra AIs you needto provide extra information foryourself or your trading partners,for example AI 10 for batchnumber

The height of the bars of all thebar codes must be a minimum of32 mm

Bearer bars should be used togive an indication of print headfailure

8 Pallet labels

23

A5 sized label

25.12.07

(02)15012345678907(17)071225(37)0110

(00)050123450001234563(10)1234AB

24

Position of label on palletMany pallets will be handled on automatic systems so it isimportant that scanners can find the bar codes easily.

For pallets taller than 1,000 mm

Place the label so that the bar codes are no higher than 800 mm and no lower than 400 mm

Use two identical labels for eachpallet, one on a short side andone on the long right hand sideas shown below

Ensure that the bar codesincluding their light margins on the label are no closer than 50 mm to a vertical edge

For pallets lower than 1,000 mm

Place the label as high aspossible but make sure that thebar codes are no higher than800mm and no lower than 32mmfrom the base of the unit

Ensure the bar codes with theirlight margins are no closer than50 mm to a vertical edge

x x>50mm

h>400mm

h

25

The accurate printing of bar codesis fundamental for effective valuechain management as the rapidand accurate scanning in of GS1data provides the basis for all theelectronic business transactionsthat follow.

Bar code scanning provides noindication of bar code quality as itgives no information about thesymbol other than whether it canbe scanned or not by thatparticular scanner. Scanners lookfor sufficient contrast between thebars and spaces, measure, anddecode the different widths ofbars and spaces into data that issent to the software system.

The GS1 General Specificationsprovide a process for theproduction of bar codes thatshould result in scannablesymbols, but a verificationprocedure needs to be followed to provide more information about symbol quality.

Staff need to be trained in the useof verification equipment, andmust always check symbolsvisually before using a verifier thatmeets the requirements of ISO/IEC15426-1 to provide detailedinformation. Each symbol must bechecked to see that the bars arethe correct height, and that nohorizontal lines or spaces cutthrough the symbol. Any markscrossing the bars and spaces of asymbol will reduce its effectiveheight and make it very difficult to scan.

The position of the bar code onthe packaging will need to bechecked to see that it meets theGS1 General Specifications. Anyfinal labelling or wrapping should also be examined to ensurethat the bar codes remain visibleand scannable.

When checking symbol quality,you should attempt to simulatethe final, filled product or package.If for example a white backgroundis printed on to a clear substrate,check the colour of the contentsof the item. If it is not possible tosimulate the contents, verify thebar code twice, once over a black background and next over awhite background. The worse ofthe two grades will provideinformation about the worstpossibility.

Having checked that the bar codes are in the correct positionand are not shortened in height(truncated), you can useverification equipment to obtainan overall grade for each symbol.

9. The verification process

26

Verifiers that meet theinternational requirements willmake measurements of and gradethe following seven parameters ofthe code:

The symbol contrast (a measureof the contrast differencebetween the dark bars and the paler background)

The minimum reflectance (acheck that the bars appear darkenough in relation to the spaces)

The minimum edge contrast (ameasure of the least difference incontrast between an adjacent barand space). This will be a lowgrade if the bar code is unlikelyto be read when it is scanned

Modulation (a ratio of theminimum edge contrast to thesymbol contrast). This grade will be low if positive bar gainhas increased the width of thebars causing a narrowing of thespaces between them

Defects (which may be lightvoids within dark bars or darkspots in the spaces between the bars)

Decode (an indication that thesymbol will decode successfully ifit conforms to the specifications,notably in respect of characterencodation, check digits andlight margins)

Decodability (an indication of theaccuracy of widths and positionsof the bars and spaces)

All of these criteria are measuredseparately and the grade given tothe bar code is the lowest scorefor any one of thesemeasurements.

All of these characteristics can bemeasured by verificationequipment which meets therequirements of ISO/IEC 15426-1,which incorporates the CEN(Comit Europen deNormalisation, the EuropeanStandards Committee) standards.These standards are compatiblewith those from ANSI (theAmerican National StandardsInstitute) and the table belowshows how they compare.

Numeric range (CEN) Alphabetic grade (ANSI)

3.5 to 4.0 A

2.5 to 3.5 B

1.5 to 2.5 C

0.5 to 1.5 D

0.5 and below F

27

This standard applies to all the bar codes used by the GS1 System,and provides a basis for agreeingthe quality of symbols acceptablewith trading partners. The gradegiven by a verifier is only anindication of the quality of a symbol. The verifier shouldideally be used to check eachsymbol ten times, using differentpaths through the symbol. Highergrades mean that the bar code inquestion is closer to the ideal thanlower scoring symbols, but theremay still be some faults that willprevent it from being decodedsuccessfully by all scanners.

The aim is to produce bar codeswith grades 4 or A, although thiswill be difficult with some printingprocesses and materials.

All bar codes must be grade 1.5 orC or above, except for ITF-14symbols printed on to fibreboard,when grade 0.5 or D is acceptable.

In general, higher quality barcodes can be expected to scanmore easily and quickly than lowerquality bar codes of the same size.Bar codes of similar sizes, with noreduction in height (truncation),and high print quality contributeto fast, effortless scanning.

Traditional verificationThe traditional approach to testingprint quality, PCS or print contrastsignal, is not formallyrecommended by the GS1 GeneralSpecifications but it is still a usefulmeans of obtaining informationabout the bar code. Mostverification equipment will be ableto report these parameters:

The width, magnification or x-dimension of the bar code

Dimensional bar widthdeviations, in particular a figurefor average bar growth

Dimensions of the light marginsat each side of the code

Print contrast signal. Thiscompares the amount of lightreflected from the bars to theamount of light reflected by thespaces and measures it as apercentage of the light from thespaces. It is a different measurefrom symbol contrast

10. Common problems to avoid

These are many of the most common problems, and some that will bediscovered with the correct use of verification equipment.

Pictures of problems Problems

The light margins required for each barcode are not large enough.

The bar codes are shortened belowtheir standard height (known astruncation).

Missing bars or horizontal whitelines crossing the bar code becauseof faulty print heads used for ondemand printing.

Choosing incorrect colourcombinations, often orange or redbars on a pale background, whichwill not scan. Reversed out images,where the bars are white against acoloured background, are again notscannable.

Using transparent or semi-transparentsubstrates, such as glass or plastic, andhoping that the contents will provide asuitable background colour either forthe bars or the spaces.

28

29


Printing bar codes that are either toolarge or too small.

Incorrect adjustment for ink spread(the bar width reduction). The printedbars are out of specification, eitherbeing too narrow or too wide.

Placing labels too close to verticalcorners or wrapping them aroundcorners so that the bar codes aretoo close to the edge.

Peeling or creased labels.

Show through of the bar codes onconsumer units through the outerpackaging.

30


Printing bar codes onto film which isdistorted as it is used as shrink wrap.

Obscuring the bar codes.

Bar code printed vertically.

Bar code printed too close to edge oflabel.

31


Same GTIN on different product lines.

Printing bar code on to packaging or alabel which is then distorted.

Poor quality substrates are substitutedfor the original specification, resultingin loss of quality, often greater inkspread, or the appearance of voids inthe bars. A darker coloured substrate,for example, could result in insufficientcontrast.

Using uncovered metal surfaces as abackground or for the bars of a symbol.The specular reflectance of thesubstrate can cause problems, and asolid background must be printed toprovide good contrast and eliminatethis problem.

Problems with GS1-128 bar codes

Printing Code 128 symbols instead of GS1-128 symbols because the mandatory Function 1 character is not included.

Encoding the brackets around the application identifiers as data within a GS1-128 bar code. These brackets are only usedaround the application identifiers in the human readable characters printed below the bar code.

Printing a GS1-128 symbol wider than 165 mm. This dimension includes the light margins which are not explicitly indicated,so special attention must be given.

Not showing the application identifiers in brackets below a GS1-128 bar code.

Not including the application identifiers required to define the data in a GS1-128 bar code.

Re-check the GTIN and check this and other encoded data in any artwork

Ensure that the check digit is correct. Ensure that the correct symbol is used for the relevant product, application and scanning environment. Check the size of the symbol, both the magnification and the bar height. Check the position of the symbol on the final, made-up product. Ensure that there are adequate light margins and that any optional light margin indicators are correctly placed. Check that the contrast between the bars and the background is adequate and that the colours chosen will scan. Make

sure that the colour of the contents of the packaging will not unduly affect the contrast between the bars and spaces.

Check the print quality regularly throughout the print run by verifying symbol quality. Check that the bar code will remain readable in the environment in which the product will be stored, handled and

distributed.

Ensure that no shrink-wrap, tape or other printing will obscure the bar code on the finished product. Ensure that no other bar code will show through from the inside of the pack. Carry out routine verification at all levels of packaging to ensure that the bar code complies with the required quality

standard, and to identify any potential problems.

Keep records of verification for the shelf life of the product. Notify trading partners of the GTINs and the products they identify in good time.

32

11. Checklist

33

EAN-8, EAN-13, ITF-14 printed ITF-14 pre-printed GS1-128UPC-E and UPC-A on label on board

Consumer unit

Traded unit (except UPC-Eand EAN-8)

Traded unit with short shelf life

Number of bar codes on consumer unit 1

Number of bar codes on traded unit 21 1 2 1

Range of x-dimension sizes 0.264 mm to 0.495 mm to 0.635 mm to 0.495 mm to

0.66 mm2 1.016 mm 1.016 mm 1.016 mm

Magnification range 80% to 200%3 48.7% to 100% 62.5% to 100% 48.7% to 100%

Target size for consumer units (x-dimension in mm) 100% (0.33 mm)

Target size for traded units (x-dimension in mm) 150% (0.495 mm) 48.7 % (0.495 mm) 100% (1.016 mm) 48.7 % (0.495 mm)

Target bar height for 100%sized EAN/UPC symbols For EAN-13, UPC-A

and UPC-E, 23 mm. For EAN-8, 18 mm

Absolute minimum barheight for consumer units4 16 mm

Minimum bar height for traded units 32 mm 32 mm 32 mm 32 mm

Bearer bar NO YES YES YES

Optional light margin indicators5 YES YES YES YES

Minimum verification grade C C D C

12. Summary of best practicerecommendations

1 A minimum of one EAN/UPC symbol is required when the traded unit is also a consumer unit.2 A minimum x-dimension of 0.25 mm is allowed for on-demand bar code production.3 A minimum magnification of 75.8% is allowed for on-demand bar code production.4 Any shortening in the height of bar codes may cause problems in markets outside the UK.5 Light margin indicators are not formally required but they may be used to provide a visual indication of the space required to the left and right of each

symbol.

34

1. Ensure EAN-13, UPC-A, EAN-8or UPC-E bar codes are used onany product that might be soldat a retail point of sale.

2. If a traded unit might also besold at a retail point of sale, itmust be bar coded with an EAN-13 or UPC-A bar code of atleast 150% magnification (equalto an x-dimension of at least0.495 mm). The actual sizechosen will depend on thechoice of printing materialsbeing used.

3. Traded units can be bar codedwith any of these symbols EAN-13, UPC-A, ITF-14 and GS1-128. Short shelf life tradedunits (those with a shelf life ofless than 42 days) will need tobe bar coded with a GS1-128bar code including the expirydate.

4. Remember that the lightmargins of any of the bar codesvary in proportion when youincrease or decrease their size.Ensure that the light marginsyou provide at each side of thebar code will be adequate, andit is good practice to allow atleast 1 or 2 mm extra on eachside to allow for any variationin the printing.

5. When printing any of the GS1bar codes on demand,incorporate horizontal bearerbars that will allow you to seeeasily whether any print headelements are failing.

6. Make sure it is not possible toscan any of the bar codes onindividual items when they areinside any outer packaging.

7. The areas needed for the barcodes at their target sizes areas follows:

Bar code Magnification Light margin width Space needed(xdimension) needed on each side* (width x height)*

EAN-13 100% (0.33 mm) 6 mm (left), 4.5 mm (right) 42 mm x 26 mm

UPC-A 100% (0.33 mm) 5 mm 42 mm x 26 mm

EAN-8 100% (0.33 mm) 4.5 mm 31 mm x 22 mm

UPC-E 100% (0.33 mm) 5 mm (left), 4.5 mm (right) 27 mm x 26 mm

ITF-14 on label 48.7% (0.495 mm) 7 mm 75 mm x 49 mm

ITF-14 on board 100% (1.016 mm) 12 mm 160 mm x 49 mm

GS1-128 showing GTIN anda date on a label 48.7% (0.495 mm) 7 mm 103 mm x 40 mm

GS1-128 showing GTIN and anet weight and a date on a label 48.7% (0.495 mm) 7 mm 131 mm x 40 mm

*These dimensions include an extra 2 mm to the minimum required on each side of the bar code to ensure that adequate light margins are provided.

35

13. Bar code management

It is good practice to assign therole of symbol quality manager to a specific individual in theorganisation. Depending on thetype of organisation, retailer ormanufacturer, the use of bar codeswill differ, which will affect thespecific role of the assignedmanager. However, their primaryobjective will be the same, toensure good quality bar codes.

For a retailer the manager willensure that the symbols scanproperly at the retail or wholesalecheckout and at the distributioncentre.

A symbol quality manager for amanufacturer will ensure thatgood quality bar codes areaccurately and consistentlyapplied to products.

36

Terms Meaning

Application identifier The two, three or four digit number that specifies the data that immediately follows it ina GS1-128 bar code.

Article number The former name for the global trade item number.

Bearer bars Horizontal bars printed above any of the bar codes when they are printed on demandthat will indicate any missing printhead elements. Also used above and below ITF-14bar codes to prevent short scans.

Bearer box The bars that surround an ITF-14 symbol to equalise the pressure exerted by theflexographic printing process over the entire surface of the symbol.

Check digit The last digit of a GTIN or SSCC that is calculated from all the preceding digits to checkthat the data has been correctly composed.

Consumer unit An item that may be sold at a retail point of sale. Also referred to as a retail trade item.

EAN-8 The eight digit bar code that represents a GTIN-8.

EAN-13 The thirteen digit bar code that represents a GTIN-13.

EAN/UPC The name of the symbology used by EAN-8, EAN-13, UPC-A and UPC-E bar codes.

GTIN Global trade item number. The unique number for a product line. This number is used ina bar code and electronic data interchange messages.

GTIN-8 The name given to the eight digit GTIN that is shown in an EAN-8 bar code.

GTIN-12 The name given to the twelve digit global trade item number formed from a UCCcompany prefix number. This may be shown in UPC-E, UPC-A, ITF-14 and GS1-128 bar codes.

GTIN-13 The name given to the thirteen digit GTIN that may be shown in EAN-13, ITF-14 or GS1-128 bar codes.

GTIN-14 The name given to the fourteen digit GTIN that may be shown in either ITF-14 or GS1-128 bar codes on traded units.

GS1 The governing body for GS1 member organisations which administers the GS1 system.

Item number Global trade item number. The new term that has replaced article number.

ITF-14 A 14-digit interleaved two of five bar code. The bar code used to show GTIN-12, GTIN-13and GTIN-14 numbers on trade items not crossing a retail point of sale.

Kraft A type of fibreboard often used for outer cases.

Ladder orientation Printing the bar code so that the bars are horizontal to the base of the product.

Light margin indicators Marks to indicate the light margins required.

14. Glossary of terms

37

Terms Meaning

Light margins The clear spaces required to the left and right of any bar code. These differ for each barcode as shown in appendix 1.

Magnification The factor used to vary the nominal size of each bar code to ensure it is scannable.

Module The smallest element (i.e. thinnest bar or space) of a bar code.

Outer case A traded unit.

Pallet label The GS1 logistics label that is used to track and identify pallets and any other transportunits.

Picket fence orientation Printing a bar code so that the bars are vertical to the base of the product.

Quiet zones Another term for the light margins.

SSCC Serial shipping container code. The unique eighteen digit identifier for a transport unit.

Specular reflectance The reflectance of light from highly polished surfaces.

Substrate The material on to which a bar code is printed.

Symbology A type of bar code symbol.

Trade item Any item that is identified for pricing, ordering and invoicing purposes. This includesboth consumer units and traded units.

Traded unit An item that is priced, ordered and invoiced between manufacturers, retailers andwholesalers. Also known as an outer case or a trade item grouping.

Transport unit A unit, for example a pallet, which is constructed for moving goods from one place toanother.

Truncation The reduction in height of a bar code when its width is unaltered.

UPC-A Universal Product Code, version A. The name for the 12 digit bar code that represents aUCC-12 global trade item number.

UPC-E Universal Product Code, version E. The name for the eight digit bar code that representsa UCC-12 global trade item number with zero suppression.

X-dimension The nominal width of the narrowest bars or spaces in a printed bar code.

Zero suppression Used by eight digit UPC-E symbols to represent a twelve digit global trade item number.

38

Appendix 1

Bar code dimensionsNominal (100% magnification) dimensions of EAN/UPC and ITF-14 bar codes. All measurements are in millimetres.

Light margins

37.29

3.63 2.31

31.35

22.85 25.93

Light margins

37.29

2.97 2.97

31.35

23.85 25.91

Light margins

26.73

2.31 2.31

22.11

18.23 21.64

Light margins

22.11

2.97 2.31

25.9322.85

EAN-8UPC-E

EAN-13 UPC-A

4.8

4.8

31.8

10.9 10.9

122.4

153.8

Light marginLight margin ITF-14

The light margin dimensions shown here are the minimum for nominal sized symbols and in practice extra space must be provided to allow forprinting variations. These light margins also change in proportion with any increase or decrease in the magnification of these symbols.

39

Appendix 2

Creating GTINs and SSCCsCompanies wishing to bar codetheir products for open trade willneed to join a GS1 memberorganisation to be assigned acompany prefix number that canbe used to create global tradeitem numbers (GTINs), serialshipping container codes (SSCCs),or any of the other GS1 identifiers.The UK member organisation isGS1 UK, previously known ase.centre.

Companies joining GS1 UK will begiven a GS1 company prefixnumber beginning with thenumbers 50. Other memberorganisations allocate companyprefix numbers beginning withdifferent numbers.

Companies will be allocateddifferent length company prefixnumbers according to theirnumbering requirements.Company prefix numbers fromGS1 UK are 7, 8, 9 and 10 digits inlength and they will be used tocreate 13 or 14 digit GTINs andSSCCs.

Global trade itemnumbers (GTINs)GTINs are unique numbers that areused to identify every differentproduct line. GS1 company prefixnumbers can be used to create 13and 14 digit GTINs, and UPCcompany prefix numbers can beused to create 12 and 14 digitGTINs. Every user should ensurethat their database can record 14digit GTINs as these numbers maybe used on products that aresupplied to them, even if a userdecides not to create 14 digitnumbers. This is especiallyimportant as future developmentsmay include a 14 digit option forthe retail point of sale.

40

Creating GTIN-13s The most commonly used barcode represents 13 digits and iscalled an EAN-13 bar code. The standard thirteen digitnumber is called a GTIN-13 and ismade up as follows:

Company prefix numbers allocatedby GS1 UK will begin with 50, but50 does not imply anything aboutthe origination of the productbeing identified.

You create these 13 digit numbersby adding the item referencedigits to your company prefixnumber, and by calculating a finalcheck digit. If you have a sevendigit prefix number, you add fivedigits before calculating the checkdigit. If you have an eight digitprefix number, you add four digits,and if you have a nine digit prefixnumber, you add three digits.

The calculation for the check digitis provided at the end of thisappendix, and a check digitcalculator is also available on theGS1 UK website at www.gs1uk.org.

It is your responsibility to allocateitem reference numbers. Basicallyevery different product line(whether a single item or a box ofthem) requires a different number.The numbers have no meaning so

it will often make sense to startwith 00000, 00001, 00002, and soon until 99999 is reached if youhave a seven digit prefix number.For eight and nine digit prefixnumbers, you should start with0000, 0001, 0002 and 000, 001, and 002 respectively.

The numberbank facility on theGS1 UK website provides you witha complete list of your companysavailable numbers, including theircorrect check digit. When you joinGS1 UK a complete list of yourcompanys available numbers isrecorded on your numberbank.Each numberbank is secure andcan only be accessed by yourcompany via the members only area of the website,www.gs1uk.org.

Company Item reference Check digit Number of item numbers prefix number that can be created

XXXXXXX XXXXX C 100,000

XXXXXXXX XXXX C 10,000

XXXXXXXXX XXX C 1,000

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Creating GTIN-12s If you are trading with companiesbased in North America you maybe using UPC bar codes for your products. These representGTIN-12s which can only becreated with a UPC companyprefix number which you will havespecially requested and paid for. The table below shows how GTIN-12s are created in exactly thesame way as GTIN-13s.

UPC prefixes being allocated toorganisations now will generallybegin with 6, 7 or 8, but someusers will have prefixes that beginwith 0. All of these prefixes mustbe used to create complete

12-digit numbers. The check digitcalculator that is available on theGS1 UK website, www.gs1uk.org,will give you the option ofchoosing GTIN-12 for thiscalculation.

Creating brandedvariable measurerestricted circulationnumbers (RCNs)Products which are not fixed inweight and are sold at a retailpoint of sale are bar coded usingbranded variable measure prefixnumbers which are available onrequest from GS1 UK. These specialprefixes are only used on itemswhich vary continuously in any

measure that affects their price,and this will often be their weight.These 13 digit RCNs include theirprice in sterling and cannot beused in other currency areas.Companies exporting theseproducts should contact GS1 UKfor details of the equivalentsystems used abroad.

These numbers are constructedas follows:

The first seven digits of thisnumber will be notified to theretailer selling these items, and areknown as the short identificationnumber. The price verifier iscalculated according to an algorithm explained in the GS1General Specifications and usesthe four digits representing theprice. The check digit is calculatedin the normal way.

The EAN-13 bar codes representingthese RCNs must be printed on-line and the selling price per unitof measure must be known beforethe labelling can begin.

Creating own-labelvariable measurerestricted circulationnumbers (RCNs)Own-label variable measure RCNswill be used by retailers sellingproducts under their own name intheir own stores. These cannot beused in open trade. The structure

generally adopted in the UK is asfollows, but some retailers maychoose not to include a priceverifier.

The price verifier is calculatedusing the five digits that precedethe check digit. These RCNs areshown in EAN-13 bar codes.

Company Item reference Check digit Number of item numbers prefix number that can be created

XXXXXX XXXXX C 100,000

XXXXXXX XXXX C 10,000

XXXXXXXX XXX C 1,000

Branded Item Price Price in Check digitvariable reference verifier sterling

20XXX XX V PPPP C

Internal Price verifier Price in sterling Check digititem reference

02XXXX K PPPPP C

Creating GTIN-14sAny member company can chooseto identify their traded units (tradeitem groupings) with GTIN-12,GTIN-13 or GTIN-14s. Somecompanies will use GTIN-14s forouter cases, and they must beshown using either ITF-14 or GS1-128 bar codes.

The numbers are created byadding an indicator as a prefix tothe GTIN-13 for a product, andthen recalculating the check digitas shown below. The indicator cantake any value from 1 to 8, andsimply creates a different itemnumber for a different packagingconfiguration. (The number 9 isonly ever used when identifyingouter cases of products of acontinuously variable measure,usually weight.) The indicator hasno meaning so all the details ofthe item being identified in thisway must be given to your tradingpartners in the normal way.

Component parts ofGTIN-14Organisations using these GTIN-14numbers can increase theirnumbering capacity significantly,but please remember that theymust only be used on trade itemgroupings.

Companies using UPC companyprefix numbers can also use thisapproach to create GTIN-14numbers, but a zero will need tobe placed after the indicator as afiller character. This will thenconvert a GTIN-12 into a newGTIN-14.

Many companies will decide notto use this basis for creating GTINs,but all systems must be able torecord these 14 digit itemnumbers.

Creating SSCCsThe same company prefix numberused to create GTINs is used tocreate serial shipping containercodes (SSCCs) that are uniqueserial numbers for each logisticsunit. Companies that have a sevendigit GS1 company prefix numbercan create up to ten billiondifferent SSCCs. Users with longercompany prefix numbers havefewer numbers to use, but theywill still create unique 18 digitnumbers.

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Indicator GTIN-13 of single item New check digitwithout its check digit

1 501234567890 7

2 501234567890 4

3 501234567890 1

4 501234567890 8

5 501234567890 5

6 501234567890 2

7 501234567890 9

8 501234567890 6

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The number has four componentsbut it must always be used as onecomplete number withincompanies computer systems.Whenever the SSCC is shown in aGS1-128 bar code it will bepreceded by the applicationidentifier 00.

The application identifier (AI) forSSCCs is always 00, and definesthe data structure.

The extension digit can take anyvalue between 0 and 9 and allowsusers to create more SSCCs. It waspreviously known as thepackaging indicator and 3 wasrecommended as a default valuefor UK users.

The serial number is between nine to seven digits in length,depending on the length of thecompany prefix number, and isallocated by the company makingup the unit. The number must notbe reused for at least one year.

A UPC company prefix number willbe prefixed with a zero when usedto create SSCCs.

Check digit calculationThe last digit of any GTIN or SSCCis a computer check digit to makesure the number is correctlycomposed. The check digit iscalculated by a modulo 10algorithm from all the other digitsin the number through thefollowing steps:

1. Starting with the digit on theright of the number, (excludingthe check digit) sum all thealternate digit values, readingright to left.

2. Multiply the result of step 1 by 3.

3. Sum all the remaining digitvalues.

4. Add the result of step 2 to theresult of step 3.

5. The modulo-10 check digit is thesmallest number, which whenadded to the result of step 4,produces a multiple of 10.

For example, to calculate thecheck digit for the GTIN-13number 501234576421_:

A series of check digit calculatorsis now available on the GS1 UKwebsite, www.gs1uk.org. They canbe accessed directly from thehome page and will producecheck digits for all the numbersmentioned here. To use the calculator simply follow the instructions and key inthe digits.

Application Extension Company prefix Serial Check identifier digit number number digit

00 X XXXXXXX XXXXXXXXX C

00 X XXXXXXXX XXXXXXXX C

00 X XXXXXXXXX XXXXXXX C

5 0 1 2 3 4 5 7 6 4 2 1 _

Step 1 1 + 4 + 7 + 4 + 2 + 0 = 18

Step 2 18 x 3 = 54

Step 3 2 + 6 + 5 + 3 + 1 + 5 = 22

Step 4 54 + 22 = 76

Step 5 76 + C = 80

ANSWER C = 4

The complete GTIN-13 number is50123456764214

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Appendix 3

Printing techniquesVirtually all consumer units(products that will be sold at aretail point of sale) and very many traded units (the outer cases forthe consumer units) will be sold inpackaging that is printed with theappropriate bar code. Some itemswill use bar coded labels andadvice about using these isprovided in the second section of this appendix.

The image of the bar code that isincluded in the artwork will needto be adjusted to take account ofthe spread of ink. This is necessarybecause direct contact printedbars in bar codes print wider thanthe actual width of bars on theprinting plate. The differencebetween the width of the bar as itis printed and the specified widthon the printing plate is called printgain.

Each bar on the printing plateneeds to be reduced in width bythe average print gain and this isknown as bar width reduction.

All widths of bar have the samebar width reduction so that thespaces on the printing plate willbe wider than they will be whenthey are printed. This adjustmentin the width of the bars can bedetermined by the use of theprintability gauges. Printers will beable to offer advice about the useof the printability gauges and filmmaster suppliers will be able tosupply images that have beencorrectly adjusted for theparticular printing process beingused.

Different printing techniques havedifferent tolerances for printingaccuracy and different print gainsso it is important to check whatthese are before choosing aparticular size of bar code. Thechoice of substrate used in theprinting process will also affect thesize of the bar code that can beaccurately printed.

If possible, when usingflexographic printing, the barsshould run parallel to the pressweb direction. If the bars arerequired to be perpendicular tothe press direction, try to avoiddistorting the symbol for the plateroll circumference. This lack ofdistortion will alter the overallwidth of the symbol, but willprovide dimensional integrity.When using either silk screen orrotogravure printing processes, the symbol must be alignedparallel to the cell structure on the screen or gravure platecylinder to provide the smoothestbar edge possible.

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Printing on demandPrinting bar codes on demand isnecessary when including variableinformation, such as expiry dates,in GS1-128 bar codes for tradedunits. Some users will want toprint bar coded labels on demandfor some consumer units,especially when these items arenot contained in pre-printedpackaging. On demand printingtechniques include direct thermal,thermal transfer, laser, iondeposition, ink jet and mechanical matrix.

First of all check that your labeldesign software is compatible withthe printer hardware you areplanning to use, and that theprinter resolution is adequate for the bar codes you are printing.In general this means that yourprinter must have a resolution of at least 8 dots per mm(approximately 200 dots per inch)as it has to use a whole number ofdots to make up the width of thenarrowest bars required.

An 8 dpmm printer will be able to print bar codes whose x-dimensions are 0.25 mm, 0.375 mm, and 0.50 mm. A 12 dpmm printer (approximately300 dots per inch) will be able toprint bars with x-dimensions of0.25 mm, 0.333 mm, 0.416 mm,0.50 mm and so on.

All on demand printers, whetherthey are direct thermal, thermaltransfer, dot matrix, ink jet or laser,will print better bar codes withwell defined edges if they areprinting the bar codes in picketfence orientation. This means thatthe bars go in the same directionas the substrate when it passesthrough the printer.

Printing in picket fence orientationmeans that the width of the barcode can be no wider than the print head.

If it is necessary to print a bar codewhich would be wider than theprint head, then it must be printedin ladder orientation. This meansthat any failure in the print headelements will cause white lines toappear across the bar code. Thesefaults in effect reduce the heightof the bar code and make it moredifficult to scan.

Matching the label stock with thetechnique being used is alsoimportant, as poor quality papercan create dust which can causethe print heads to burn out soonerthan expected. It is also necessaryto match thermal transfer ribbonsto the equipment being used, andensure that the correct pressuresare being used with the printheads. The incorrect choice ofribbon and paper may beworkable, but the machinery islikely to require much highermaintenance costs and requiremuch more frequent servicing. It is highly recommended to usevalidated combinations of ribbonsand labels, and to use verificationequipment to check the printquality.

Direct thermal printing may beappropriate for some products,and the correct label stock mustbe sourced. Bear in mind thatthese labels remain heat sensitiveand may be inappropriate if goodsare kept in direct sunlight or if the labels are heated in anysubsequent process.

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Appendix 4

Printing GS1-128 barcodesThese bar codes are nearly always printed on demand, so the operator of the equipmentneeds to be aware of certainrequirements.

Function 1GS1-128 symbols are a subset ofCode 128 and they require aspecial symbol character (a pattern of three bars and threespaces) called Function 1 to beused as part of the start pattern. Ifthe Function 1 character is notcorrectly included as part of thestart pattern the symbol will notmeet the requirements of the GS1System.

Choosing the correct charactersetThere is a choice of character setsto help users minimise the spacetaken up by these bar codes. Usecharacter set C to print pairs ofdigits using one symbol character(a pattern of three bars and threespaces) rather than two symbolcharacters whenever possible. Ifsingle letters or numbers arerequired use character sets B or A.

ConcatenationConcatenation is an effectivemeans for encoding severalelement strings in a single barcode and should be used to savelabel space and optimise scanningoperations.

The element strings may appear inany order in a GS1-128 bar code.

The best practice is to put data offixed length before any variabledata to minimise the length of thebar code. If a variable length fieldis followed by another elementstring, it must be terminated bythe Function 1 character. When avariable length field appears at theend of a GS1-128 bar code it doesnot need to be terminated by theFunction 1 character.

The SSCC, defined by the AI 00,must always appear in the lowestbar code on the label. The SSCC

can be alone or concatenated withother data in the same bar code.Concatenation cannot be usedwith the SSCC on standard A6labels because the bar code wouldbe too wide for the label.

Choosing the correct sizeGS1-128 bar codes can vary in size according to how well theycan be printed. The maximumwidth for the x-dimension (thewidth of the narrowest bars andspaces) is 1.016 mm and theminimum x-dimension is 0.495 mm when these bar codesare used on trade item groupings.

Users must choose an x-dimensionthat can be reproduced by theiron demand printing equipment.The x-dimension must be amultiple of the size of the smallestline that can be printed, and if an 8 dpmm (200 dpi) printer is used,the x-dimensions can be 0.50 mm,0.625 mm, 0.75 mm, 0.875 mmand 1.00 mm.

If users are using labels, an x-dimension of 0.50 mm will beacceptable, provided the printedbar codes, when verified, meet theminimum grade required.

If users are printing these GS1-128bar codes directly onto fibreboardoutercases an x-dimension of 1.00mm is recommended, but verifiersmust still be used to check thatthe bar codes meet the minimumgrade required. Furtherinformation about verification isprovided in section 9.

Enlarged section of first part of a GS1-128 bar code showing theFunction 1 character in blue.

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Height of bars Whichever x-dimension is chosen,the height of the bars must be atleast 32 mm.

Keeping adequate light marginsThe light margins on each side of a symbol which has an x-dimension of 1 mm are 10 mm.The light margin is always equal to10 times the x-dimension, butwhen the x-dimension is 0.50 mmit is recommended that the lightmargins are at least 7 mm on eachside.

When are brackets requiredaround the applicationidentifiers?Brackets are used around eachapplication identifier (AI) when thedata is printed below the bar code.This makes it easier for people toread the AI and the data it defines.The brackets are not encoded intothe GS1-128 bar code itself and donot appear around the AIs whenthey are mentioned elsewhere.

Determining the length of a GS1-128 bar codeGS1-128 bar codes will vary inlength if they include differenttypes of information so it isimportant to check that theintended length of the bar code,with the necessary light marginsto the left and right, is no longerthan 165 mm. Each symbolcharacter (except the stopcharacter) has a width of 11 mm ifan x-dimension of 1 mm is chosen,and each symbol must includefour symbol characters to beginand complete the bar code.

For example, how long will a GS1-128 bar code be that includesa GTIN and an expiry date? Thedata required in the bar code is all numeric so character set C willbe chosen.

The data required in the bar codewill be as follows:

010501234567890017060606.

The bar code begins with Start Cand Function 1 characters andends with a symbol checkcharacter and the stop character.The 24 numbers required in thebar code will be shown by 12symbol characters in this characterset, so the complete symbol willbe 16 symbol characters in length.

The width of the bar code (if an x-dimension of 1 mm ischosen) will be:

(16 x 11) mm + 2 mm extra for thestop character + 20 mm for thetwo light margins

176 + 2 + 20 = 198 mm.

This measurement exceeds themaximum allowed length so the x-dimension must be reduced. Ifan x-dimension of 0.50 mm ischosen the bar code will be halfthis length, 99 mm.

If an x-dimension of 0.625 mm ischosen the length will be 123.75 mm, and with an x-dimension of 0.75 mm, thelength will be 148.5 mm.

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Choosing the correct applicationidentifiersWhen providing extra informationon a traded unit, most users willencode the GTIN for the productwith information such as an expirydate. The GTIN on the item mustbe specified by the AI 01, and theextra information defined usingthe AIs as explained in the GS1General Specifications. The mostcommonly used AIs and their fieldlengths are given below.

When labelling pallets, the GS1logistics label must be used. Allthe data shown on the label mustrefer to the contents of the wholepallet. The SSCC is the onlycompulsory element, and will bethe only reference used on palletsof mixed product.

For pallets with uniform contents,any of the AIs listed below can be used. Please remember that youcannot use AIs 01 and 02 together.

AI 01 must only be used when thepallet is also a traded unit, ie. it isordered and invoiced as a singleitem. In all other cases, use the AIs02 and 37 to describe the contentsof the pallet.

AI Description Format

00 Serial shipping Fixed length, 18 digits Has to be used on all GS1 logistics labelscontainer code

01 Identification of trade item Fixed length, 14 digits

02 Identification of the Fixed length, 14 digits Must not be used with AI 01 identification of a content of a logistics unit trade item

10 Batch number Variable length, up to Each AI must only be used once on each label; mixed20 alphanumeric characters batches and mixed product variants cannot be

identified using the AI standards

15 Best before date YYMMDD, fixed length, 6 digits The pallet must contain products with the samebest before date

17 Use by date YYMMDD, fixed length, 6 digits The pallet must contain products with the sameexpiry date

20 Product variant Fixed, 2 digits

21 Serial number Variable length, up to Cannot be used to identify more 20 alphanumeric characters than one item

37 Count of trade items Variable length, up to 8 digits Must not be used with AI 01contained

3102 Net weight in kilos to Fixed length, 6 digits Must only be used with a variable measure GTIN-14two decimal places

This is not an exhaustive list of all the application identifiers that can be used on traded units or on pallets. Please consult

the GS1 General Specifications to find a complete listing of all the AIs.

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Appendix 5

Symbol show throughWhen a traded unit is bar coded itmust not be possible to read anyof the bar codes on the consumerunits inside the packaging. If thebar codes can be read, there is agood chance that one of these willbe read instead of the correct oneon the outside of the case. Thisproblem is called symbol showthrough.

When show through takes place itmakes it very difficult to use anautomatic scanning system reliably as the wrong item may bescanned. This means incorrect data capture and the wrong pricebeing charged at the point of sale.

This is a particular problem forcash and carry retailers who sellboth traded and consumer unitsto their customers. They cannotchoose to read only, say ITF-14 andGS1-128 bar codes, at their pointsof sale as they do need to be ableto read EAN-13 symbols onconsumer units as well.

This problem also affects groceryand other retailers who sell largemultipacks which are also tradedunits. Care must be taken to avoidpackaging consumer units so thattheir bar codes are visible in theirentirety. Recent packaging wastedirectives are encouraging manymanufacturers to make more useof shrink wrapping, and usingpatterned or obscuring film maybe considered as a means ofmaking consumer unit bar codesunreadable.

If the consumer units arerectangular in plan it may bepossible to ensure that all the bar codes on the individual itemsface inside the outer case, but thiswill not be feasible with roundproducts such as cans and bottles.When consumer units are packedon cardboard trays and then shrinkwrapped, show through can beavoided by printed the bar codesin ladder orientation and towardsthe bottom of each consumer unit.This will mean that the edges ofthe tray will obscure part of theconsumer units bar codes andmake them unscannable.

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Appendix 6

How x-dimensions andmagnification factorscompareEach bar code has a modulardesign, in that the different widthsof bar and space (and the quietzones or light margins) are allmultiples of the width of amodule. The module width is thesame as that of the narrowest baror space, and this is also known asthe x-dimension.

When EAN-8, EAN-13, UPC-A andUPC-E bar codes are at theirnominal size, the x-dimension is0.33mm. This means that thewidths of the bars and spaces ofthese particular symbols should beone, two, three or four times 0.33 mm. When any one of thesebar codes is made larger orsmaller, the symbol is kept inproportion, so a wider bar code isalso taller.

If the size of ITF-14 or GS1-128 barcodes is varied, only their widthchanges, as the height of the barsmust be 32 mm for use on tradedunits or pallet labels. This meansthat referring to the size of thesebar codes in terms of their x-dimension is more appropriate,as only one aspect of the symbol ischanging.

The relationship between x-dimension and nominal size isnot the same for all bar codes. Inthe GS1 system there is one for theEAN/UPC bar codes, and anotherfor the ITF-14 and GS1-128 barcodes. These two relationships areshown in the tables right:

x- dimension explainedThere are only four widths of black and white elements in EAN-8, EAN-13,UPC-A and UPC-E bar codes

The width of the smallest bar or space is called the x-dimension; all otherelements are multiples of this dimension.

x 2x 3x 4x

x-dimensions and magnifications forEAN/UPC bar codes

x-dimension Magnification

0.25 mm 75.75%

0.264 mm 80%

0.33 mm 100%

0.495 mm 150%

0.66 mm 200%

x-dimensions and magnifications forITF-14 and GS1-128 bar codes

x-dimension Magnification

0.495 mm 48.7%

0.635 mm 62.5%

1.016 mm 100%

This booklet only provides asummary of the GS1 specificationsfor the bar coding of goods thatare handled in open trade. If theapplication of any of this advice isunclear, please contact the staff atGS1 UK for clarification.

The complete GS1 GeneralSpecifications are available free ofcharge via the GS1 UK website atwww.gs1uk.org.

Further information and advice arealso available from the bar codemanager at each relevant retailerand wholesaler, as well as from thestaff of GS1 UK. Initial calls to GS1UK should be made via themembership services helpdesk on 020 7655 9001 or [email protected].

Information about ISO/IEC, CEN and ANSI standards isavailable from the BritishStandards Institution, 389 Chiswick High Road, London, W4 4AL, website: www.bsi-global.com, or telephone 020 8996 9000.

Further information

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DisclaimerThe objective of this document is toprovide GS1 UK members with userfriendly and simple bar coding bestpractice guidelines. The document is notexhaustive and does not replace theGS1 General Specifications whichremain the standard referencedocument.

Whilst every effort has been made to ensure that the contents of thisdocument are correct, GS1 UK, and anyother party involved in the creation ofthe document hereby state that thedocument is provided without warranty,either expressed or implied, of accuracyor fitness for purpose, and herebydisclaim any liability, direct or indirect,for damages or loss relating to the useof the document. The document maybe modified from time to time, subjectto developments in technology,changes to the standards, or new legal requirements.

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These guidelines for best practice have the support of many GS1 UKmembers including the following companies andorganisations:

Axicon Auto IDBooker Cash & CarryH J Heinz CompanyIGDIceland FoodsISIS IntegrationNestl UKMasterfoodsSainsburys SupermarketsTesco StoresUnileverWaitroseWilliam Morrison Supermarkets

10 Maltravers Street London WC2R 3BXT +44 (0)20 7655 9000F +44 (0)20 7681 2290E [email protected] +44 (0)20 7655 9001

www.gs1uk.org

GS1 UK sponsoring members

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