GS1 Bar Codes



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Ten Steps to Bar Code Implementation

(These notes are intended for use in conjunction with more detailed GS1 documents and should not be used as a sole source of technical advice.  Bar code printing is complex and technical.  Faulty bar codes may lead to rejection of products by customers.  Consult GS1 or a GS1 Accredited print company for advice on specifics). 

  1. Step 1: Get a GS1 Company Prefix
  2. Step 2: Assign Numbers
  3. Step 3: Select a Bar Code Printing Company
  4. Step 4: Select a "Primary" Scanning Environment
  5. Step 5: Select a Bar Code
  6. Step 6: Pick a Bar Code Size
  7. Step 7: Format the Bar Code Text
  8. Step 8: Pick a Bar Code Colour
  9. Step 9: Pick the Bar Code Placement
  10. Step 10: Build a Bar Code Quality Plan

 

Step 1: Get a GS1 Company Prefix

Before a company can begin using bar codes, they must create the numbers that go inside the bar code. These numbers are called GS1 Identification Keys. The first step in building a GS1 Key is to obtain a GS1 Company Prefix from GS1 New Zealand. GS1 Company Prefixes are used to identify over 1 million companies today and form the foundation of uniquely identifying everything in the supply chain. To obtain a GS1 Company Prefix you need to become a member of GS1 New Zealand.

 

Step 2: Assign Numbers

After receiving a GS1 Company Prefix, a company is ready to begin assigning identification numbers to their trade items (products or services), themselves (as a legal entity), locations, logistic units, individual company assets, returnable assets (returnable pallets, kegs, tubs), and service relationships.

The process is fairly simple and starts with the "bar code number," correctly called the Global Trade Item Number GTIN). You learn about how to format each number then use the GS1 Company Prefix in combination with reference numbers you assign. GS1 New Zealand can provide you with specific information about how many numbers you can assign based on the length of your GS1 Company Prefix.

 

Step 3: Select a Bar Code Printing Company

To begin, you should decide what you are bar coding and if the bar code will carry static or dynamic information inside it. An example of static information would be simply a product identification number GTIN on a cereal box. An example of dynamic information would be printing serial numbers on product labels.

If your bar code has static information and you need a large volume of labels then you will likely ask a printing company to print your labels. If you need a small volume of labels or need to print labels with dynamic information you will likely need an on-demand printer like a laser printer in your office or thermal transfer printer in your warehouse.

When engaging a print company ask them to assure you that they are fully aware of the provisions of GS1 General Specifications and when ordering any job specify that bar codes they print for you are fully compliant with the specifications.  A GS1 Accredited company will fulfil these requirements.  If purchasing on-demand printing equipment obtain an assurance from the supplier that the equipment will produce fully GS1-compliant bar codes and ensure that any instruction you receive in the use of the equipment enables you to do so.  Many suppliers of on-demand print equipment are GS1 Accredited.

Note that GS1 Accreditation is a specific status of GS1 membership.  Being a GS1 member is not GS1 Accreditation.  GS1 Accreditation involves special training and equipment.  Accredited companies will hold a Certificate of Accreditation and will have an eighteen - digit accreditation number. They are separately listed among Solution Providers and they may display this logo:

Scannable and non-scannable bar code colours

Bar codes must consist of two colours, the darker of which must be the bars.  The contrast between light and dark must be strong.  Bars printed on clear transparent surfaces will rarely produce a workable bar code because the background colour will depend on the product or material ultimately placed inside the packaging.  GS1 strongly advises against printing bars of clear material with no coloured background.

Scanners use red light to "see" so they do not perceive colours as humans do.   The illustration below demonstrates how some colour combinations can be ‘seen' by scanners.  (In the ‘Non-scannable' column the top two bar codes would appear as negatives to scanners and the lower two would be invisible).

 

                  

Step 4: Select a "Primary" Scanning Environment

The specifications for bar code type, size, placement, and quality all depend on where the bar code will be scanned.

There are four basic scanner environment scenarios for trade items:

  • Product package scanned at the retail point-of-sale (POS)
  • Product package scanned in a general distribution
  • Product package scanned at POS but also scanned in distribution
  • Special environments like medical device marking

By knowing where your bar code will be scanned you can establish the right specifications for its production. For example, if a product package is scanned at Point-of-Sale (POS) and in general distribution, you will need to use an EAN/UPC symbol to accommodate POS but print it in a larger size to accommodate distribution scanning and ensure the placement meets automated distribution scanning requirements.

You can find more information in the GS1 General Specifications

 

Step 5: Select a Bar Code

Selecting the right bar code is critical to the success of your bar code implementation plan, but here are some high level tips:

  • If you bar code a trade item that will be scanned at the retail point-of-sale (POS), you must use an EAN/UPC symbol.  This term covers the usual 'retail' bar codes, which are the only ones that retail scanning systems can read.
  • Remember that only the EAN/UPC bar codes and - in special cases - some of the GS1 Databar (RSS) symbols can be scanned at POS.  All of the others are intended for use in distribution.
  • If you are printing a bar code with variable information like serial numbers, expiry dates, or measures, then you will use GS1-128, GS1 DataBar(RSS), or in special cases Composite Component or Data Matrix symbols.
  • If you just want to print a bar code carrying GTIN on a corrugated carton, ITF-14 may be the choice for you.
  • See what these bar codes look like (global site).

There are other factors to consider so contact GS1 New Zealand to see what implementation products and services are offered.

 

Step 6: Pick a Bar Code Size

After the correct bar code symbol is specified together with the information to encode in it, the design stage begins. The size of the symbol within the design will depend on the symbol specified, where the symbol will be used, and how the symbol will be printed.  The larger a symbol, the easier it is to print the required standard and the more reliably it will scan so larger sizes are always the better choices.

EAN/UPC Symbols

EAN/UPC Symbols differ from ITF-14 and UCC/EAN-128 Symbols because they are scanned by retail omni-directional scanners. This means that EAN/UPC Symbols have a fixed relationship between symbol height and width. When one dimension is modified, the other dimension should be altered by a proportional amount.

Because of this relationship, EAN/UPC symbols have a nominal height and width specified. A range of allowable sizes from 80% to 200% of the nominal size are also specified and a figure showing the range of dimensions can be found in GS1 General Specifications, Section 5.1, Appendix 7. This information is available in a simpler format in Bar Coding Basic User Guide available from GS1 New Zealand. This range of sizes is often referred to as "magnification factors" on purchase orders specifying EAN/UPC Symbol sizes.

EAN/UPC Magnification

Minimum (80%)

Minimum EAN/UPC bar code size


Nominal recommended (100%)

Nominal EAN/UPC bar code size


Maximum (200%)

Maximum EAN/UPC bar code size



It is important to print EAN/UPC symbols at their correct height. The widely held belief that they may be shortened (truncated) is wrong.  They may be printed at greater heights than those specified, but not less.

When EAN/UPC Symbols are used in logistics (shipping and distribution) as well as at the Point-of-Sale (POS), the range of magnification allowed is limited to between 150% and 200%. An example of this would be the symbol on a carton used for a large appliance (e.g. TV or microwave oven).

ITF-14 and GS1-128 Symbols

ITF-14 and GS1-128 symbols also have a range of sizes specified. ITF-14 and GS1-128 symbol sizes are often specified by the width of the X-Dimension instead of magnification values. The X-Dimension simply stated, is the width of the narrowest bar in the symbol. You can find information on the sizes for ITF-14 and GS1-128 symbols based on the application where they are used or the identification number they carry in GS1 General Specifications, Section 5.4.2.

Consideration of the Printing Process

The final major consideration for symbol size is the capability of the selected printing process. The minimum size (magnification) and correct Bar Width Reduction (BWR) for a symbol varies by printing process and even from press to press. Printing companies should establish a minimum symbol size (magnification) and BWR to achieve acceptable and repeatable quality results. Larger symbols are always easier than smaller ones to print the required standard and will scan more reliably.

As always, be sure to contact GS1 New Zealand for additional implementation guidance. 

 

Step 7: Format the Bar Code Text

The text beneath a bar code is important because if the bar code is damaged or of poor quality to begin with, then the text is used as a back-up. Click here for some examples of text formatting (global site).

The best way to cover questions about the Human Readable Interpretation for GS1 System Bar Code Symbols is to answer some of the more frequently asked ones.

Does the Human Readable Interpretation need to be a certain size?

The OCR-B font was originally specified for use with EAN/UPC Symbols, but GS1 System specifications now permit any font as long as it is clearly legible. For detailed size specifications for EAN/UPC Symbols, see GS1 General Specifications Section 5.1, Appendix 6, or the Basic User Guide available from GS1 New Zealand.

The human-readable text for ITF-14 and GS1-128 Symbols must be clearly legible and in a size proportional to the symbol size as per GS1 General Specifications Section 5.2.1.6 (ITF-14) and Section 5.3.7.4 (GS1-128), or the Basic User Guide available from GS1 New Zealand.

Is the Human Readable Interpretation supposed to be above or below the symbol?

It depends on the symbol you are using. For EAN/UPC Symbols, refer to the drawings in the GS1 General Specifications Section 5.1, Appendix 6. For ITF-14 and GS1-128 Symbols the text can be printed above or below the symbol as per GS1 General Specifications Section 5.2.1.6 (ITF-14) and Section 5.3.7.4 (GS1-128), or the Basic User Guide available from GS1 New Zealand.  If necessary the text may be printed alongside as near as possible to the symbol and preferably to the left of the quiet zone.

Can I put spaces in between the text characters?

Yes, in fact, the characters beneath AN/UPC Symbols require spacing as shown in the drawings referenced in the question above. Many companies specify spacing in between ITF-14 and UCC/EAN-128 Human Readable Interpretation. This makes the text easier to read, remember, and key enter. While including spaces is perfectly appropriate for the Human Readable Interpretation, the spaces must not be encoded into ITF-14 or GS1-128 Symbols.

I see parentheses (brackets) around the Application Identifiers (AI) in the GS1-128 Symbol. Are they supposed to be there and are they encoded in the bars and spaces of the symbol?

All AIs must be enclosed in parentheses in the Human Readable Interpretation, but the parentheses are not encoded in the symbol.

How many digits do I print beneath the EAN/UPC Symbol in the Human Readable text?

  • You must, absolutely and without exception, print 12 digits, no more, no less, below the UPC-A Symbol.
  • You must, absolutely and without exception, print 13 digits, no more, no less, below the EAN-13 Symbol.
  • You must, absolutely and without exception, print eight digits, no more, no less, below UPC-E and EAN-8 Symbols.

Step 8: Pick a Bar Code Colour

The optimum colour combination for a bar code symbol is black bars with a white background (spaces and Quiet Zones). If you want to use other colours, the following may help you in choosing satisfactory ones:

GS1 Bar Code Symbols require dark colours for bars (e.g., black, dark blue, dark brown or dark green).  On no account use red for bars, because scanners cannot 'see' red.

The bars should always consist of a single line colour and should never be printed by multiple imaging tools (e.g., plate, screen, cylinder).

GS1 Bar Code Symbols require light backgrounds for the Quiet Zones and spaces (e.g., white, or yellow).  Red is a good background colour.

In many cases the symbol background is not printed. It is the colour of the substrate that is being printed. If the symbol background is printed beneath the bars, the background should be printed as solid colour.

If you use multiple layers of ink to increase the background opacity, each layer should be printed as a solid.

If you use a fine screen to deliver more ink to the substrate, be sure there are no voids in the print caused by the screen not adequately filling in.

Again, by staying with black bars and white spaces, you have selected the optimal combination, but other colour combinations can be used. Consult an experienced printer for additional guidance.

 

Step 9: Pick the Bar Code Placement

When discussing symbol location we are referring to the symbol placement on the design. When assigning symbol placement the packaging process should be considered. You should consult the packaging engineer to make sure the symbol will not be obscured or damaged (e.g., over a carton edge, beneath a carton fold, beneath a package flap, or covered by another packaging layer). To determine the proper location for GS1 bar codes, see the following sections of the GS1 General Specifications :

  • Logistics Label Design, Section 2.2.4.4
  • General Placement Principles, Section 6.2
  • General Placement Guidelines for the Retail Point of Sale, Section 6.3
  • Placement Guidelines for Specific Package Types, Section 6.4
  • Symbol Placement for Clothing and Fashion Accessories, Section 6.5
  • General Format Guidelines for Clothing and Fashion Accessories Labels, Section 6.6
  • General Placement Guidelines for Symbol Placement on Items used in Distribution, Section 6.7

After determining the proper placement, the printing company should be consulted before assigning the symbol rotation. This is because many printing processes require bar codes to be printed in a specific orientation to the feed direction of the web or sheet.

If possible, when using flexo-graphic printing, the bars should run parallel to the press web direction or in the picket fence orientation. If the bars are required to run perpendicular to the press direction or in the ladder orientation, try to avoid distorting the symbol for the plate roll circumference.

When using either silk screen or rotogravure printing processes, the symbol should be aligned parallel to the cell structure on the screen or gravure plate cylinder to provide the smoothest bar edge possible.

For more information or to obtain a copy of the GS1 General Specifications, contact GS1 New Zealand.


Step 10: Build a Bar Code Quality Plan

ISO/IEC 15416 Bar Code Print Quality Test Specifications for Linear Symbols describes a method for assessing the quality of bar code symbols after they are printed. An ISO-based verifier is an instrument that looks at the symbol in the way a scanner does, but goes further by grading the symbol's quality.

GS1 utilises the ISO/IEC method, but specifies the minimum grade necessary for every GS1 bar code based on which symbol is used, where it is used, or what identification number it is carrying. In addition to the minimum grade, GS1 also specifies the verifier aperture width and wavelength.

Users should incorporate bar code quality and number integrity into their other quality options including

  • writing a policy that ensures correct numbering, correct bar code selection, design and placement, and routine sending of bar code samples to GS1 New Zealand forverification.
  • owning and operating a verifier (see below) and conducting their own tests.
  • becoming anaccredited company, licensed by GS1 New Zealand to issue verification reports on their own products.

GS1 General Specifications Section 5.4.2.8 provide a quick reference list of symbol quality specifications. These are also set out in the Basic User Guide available from GS1 New Zealand.

GS1 members may choose to perform their own quality control of bar code production but GS1 New Zealand offers bar code quality verification services.

(These notes are intended for use in conjunction with more detailed GS1 documents and should not be used as a sole source of technical advice.  Bar code printing is complex and technical.  Faulty bar codes may lead to rejection of products by customers.  Consult GS1 or a GS1 Accredited print company for advice on specifics).