Chapter 29: Government Property Management |
A Short Summary |
This chapter explores the role of Code 39 barcodes in government property management, focusing on the U.S. General Services Administration's use of the symbology for tracking office furniture and IT equipment. It begins with a practical example of GSA asset inventory audits using Code 39 labels, then examines the technical characteristics that make Code 39 suitable for this and other applications. The chapter surveys how Code 39's specific features---its alphanumeric capacity, self-checking property, low data density, and wide scanner compatibility---influence its adoption across diverse industries including defense, automotive, healthcare, libraries, and manufacturing. Through these real-world examples, the chapter demonstrates how the symbology's strengths and limitations shape its use in each sector, and concludes with a comprehensive summary of technical considerations for practical implementation. |
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1. A Desk, A Barcode, and An Audit |
On a quiet Tuesday morning in a federal office building in Washington, D.C., a government property management specialist walks through a corridor lined with identical cubicles. She carries a handheld laser scanner---a device that has changed little in outward appearance over the past three decades---and begins her routine: inspecting each desk, each monitor, each chair, and each desktop computer. On every asset, a small label bears a series of black bars and white spaces, accompanied by human-readable text beneath. She aims the scanner, hears a confirming beep, and moves on. By the end of the day, the inventory system will reflect the presence of every tagged item, reconciling physical assets against the official government ledger. |
This is not a scene from the distant past, nor is it a legacy procedure awaiting replacement. It is a daily reality for the U.S. General Services Administration (GSA), the agency responsible for managing federal property. The barcode on every tagged item is most often a Code 39 symbology---a technology introduced in 1974, now entering its sixth decade of continuous service. Its persistence is not accidental. Code 39, also known as Code 3 of 9, has become a quiet workhorse of government and industrial asset tracking, chosen not for its novelty but for its reliability, simplicity, and universal compatibility. |
This chapter examines how the technical characteristics of Code 39 barcodes shape their use across multiple industries, using GSA property management as a central case study. We will explore why an 'old' technology continues to thrive in an age of QR codes and Data Matrix symbols, and how its specific encoding method, error-checking design, and space requirements influence its suitability for various applications. |
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2. The GSA and the Challenge of Property Management |
The U.S. General Services Administration manages a vast portfolio of federal assets. This includes office furniture, information technology equipment, vehicles, and real estate across thousands of federal facilities. Every item must be accounted for, its location tracked, its condition monitored, and its lifecycle managed from acquisition to disposal. The scale of this task is staggering. Federal agencies collectively hold billions of dollars in personal property, and the GSA is responsible for establishing policies and systems to ensure this property is properly inventoried and safeguarded. |
Asset inventory audits are the cornerstone of this accountability. These audits require physical verification that items recorded in the property system actually exist, are in the correct location, and are properly maintained. The audits are conducted on a regular basis---annually for sensitive items, periodically for general property. Without an efficient identification system, such audits would be prohibitively labor-intensive and error-prone. |
This is where barcodes enter the picture. By affixing a machine-readable label to each asset, auditors can scan items rapidly, eliminating manual data entry and transcription errors. The choice of barcode symbology, however, is not arbitrary. It must meet several requirements: the ability to encode alphanumeric identifiers (since government asset tags typically combine letters and numbers), the tolerance for printing on durable labels that may be exposed to wear, and compatibility with existing scanning infrastructure across numerous agencies. |
The GSA's adoption of Code 39 for office furniture and IT equipment reflects a deliberate decision based on these criteria. Code 39's ability to encode uppercase letters and digits directly---without requiring special encoding modes---makes it straightforward for asset identification numbers that often include prefixes like 'FURN' or 'IT' followed by serial numbers. Additionally, its self-checking property provides some inherent error resistance without requiring the computation and storage of check digits for every label. |
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3. Understanding Code 39: Technical Foundations |
Before we explore the diverse applications of Code 39, we must understand how it works. The symbology's technical characteristics directly explain why it is chosen---or avoided---in various contexts. |
3.1 The '3 of 9' Name |
Code 39 received its most common nickname from its fundamental encoding structure. Each character in the Code 39 character set is represented by a pattern of nine elements: five bars and four spaces. Of these nine elements, exactly three are wide, and the remaining six are narrow. This 'three of nine' design gives the symbology its name. |
The width ratio between wide and narrow elements is typically set between 2.5:1 and 3:1, though the specification allows for some variation. A scanner detects the presence of wide versus narrow elements by measuring the duration of each bar and space as the scanning beam passes over them. The discrete nature of the encoding---each character is independently formed and separated by a narrow inter-character gap---makes the symbology relatively tolerant of printing imperfections. |
3.2 Character Set and Encoding |
The standard Code 39 character set includes 43 characters: uppercase letters A through Z, digits 0 through 9, and seven special characters: space, minus (-), period (.), dollar sign ($), slash (/), plus (+), and percent (%). An additional character, typically represented in human-readable text as an asterisk (*), serves as both the start and stop delimiter for the barcode. Notably, the asterisk is not an encodable data character---it exists solely to mark the beginning and end of the symbol. |
This character set is sufficient for a wide range of applications, particularly those involving inventory identifiers that use alphanumeric codes. However, it cannot directly encode lowercase letters or the full ASCII character set. For applications requiring these, an extension known as Code 39 Extended (or Full ASCII Code 39) was developed, which uses pairs of standard Code 39 characters to represent all 128 ASCII characters. The trade-off is that encoding a lowercase letter or extended character requires twice the physical space. |
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3.3 The Self-Checking Property |
One of Code 39's most important technical features is its self-checking nature. Because each character's pattern consists of exactly three wide elements out of nine, a single printing defect or scanning error that changes one bar or space from wide to narrow (or vice versa) will generally produce a pattern that does not correspond to any valid character. The decoder can then reject this invalid pattern, preventing the substitution of one character for another. |
To understand why this matters, consider the alternative: a barcode symbology that lacks self-checking might misread a damaged character as a different but still valid character, silently introducing errors into the data. Code 39's design reduces this risk significantly. |
This self-checking property does not mean check digits are never used. Many specifications, including the military standard MIL-STD-130, mandate the inclusion of a Modulo 43 check digit for additional safety. However, the check digit is optional in the base specification, and many applications---especially those with relatively short identifiers and robust printing quality---rely on the self-checking mechanism alone. |
3.4 Data Density and Physical Dimensions |
The most significant limitation of Code 39 is its low data density. Because each character requires nine elements (plus the inter-character gap) and uses relatively wide bars, a Code 39 barcode is notably longer than other symbologies for the same data. A 10-character Code 39 barcode is roughly 40% wider than the equivalent Code 128 symbol. |
This has practical consequences. Code 39 is not suitable for labeling very small items where label space is constrained. It also imposes requirements on label size and printing resolution: a minimum X-dimension (narrow bar width) of 0.191mm (7.5 mils) is recommended for general use, and the quiet zones---the blank margins on either side of the barcode---must be at least ten times the X-dimension. For a typical implementation, this means a Code 39 barcode containing a 10-character identifier might need approximately 53mm of horizontal space, excluding quiet zones. |
3.5 Simplicity and Integration |
Despite its density limitations, Code 39 offers a significant advantage: ease of integration. Since no check digit is required for basic operation, systems can generate Code 39 barcodes simply by installing a Code 39 font on a printer and printing the raw data in that font, surrounded by asterisk delimiters. This contrasts with symbologies that require complex checksum calculations or encoding logic. For legacy systems or simple internal tracking, this simplicity makes Code 39 an attractive option. |
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4. Industry Applications: Where Code 39 Thrives |
Code 39's technical characteristics---alphanumeric capacity, self-checking, moderate density, and wide compatibility---make it suitable for a variety of industrial and commercial applications. The following sections examine how these characteristics play out in different sectors. |
4.1 Government and Defense: The LOGMARS Legacy |
The U.S. Department of Defense was an early adopter of Code 39 through the LOGMARS (Logistics Applications of Automated Marking and Reading Symbols) program. LOGMARS established Code 39 as the standard for marking military shipments and equipment, defining where barcodes must be placed and what information they must encode to meet military specifications. |
The military's requirements are stringent: labels must be readable under field conditions, withstand harsh environments, and remain scannable even with some wear. Code 39's self-checking property and tolerance for printing variations make it well-suited to these conditions. The military specification MIL-STD-130, which governs the identification marking of U.S. military property, mandates the use of Code 39 with a Modulo 43 check digit for added data integrity. |
This military adoption had a cascading effect. Defense contractors supplying parts and equipment to the military had to implement Code 39 in their own operations, spreading the symbology throughout the defense industrial base. Even today, with newer symbologies available, Code 39 remains entrenched in this sector due to the immense cost of changing established labeling systems and the continued adequacy of the symbology for the task. |
The GSA's use of Code 39 for office furniture and IT equipment follows directly from this tradition. Federal agencies often align their property management practices with military standards, either through policy requirements or through a desire for consistency across the broader government property system. The GSA's adoption reinforces the symbology's position as the default for government asset tracking. |
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4.2 Automotive Industry: AIAG Standards |
The automotive industry relies heavily on Code 39 through the standards established by the Automotive Industry Action Group (AIAG). AIAG's B-1 standard specifies labeling requirements for parts and components moving through the automotive supply chain. |
In automotive manufacturing, parts must be tracked from the initial supplier through multiple tiers of assembly, eventually reaching the final vehicle assembly line. Barcodes on parts contain information such as part numbers, quantities, manufacturer codes, and date codes. The alphanumeric capacity of Code 39 is well-suited to these part identifiers, which often combine letters and numbers in structured formats. |
The automotive supply chain is heterogeneous, involving thousands of suppliers with varying levels of technological sophistication. Code 39's simplicity and compatibility with virtually any barcode scanner make it a safe choice for this environment. Suppliers can implement Code 39 without investing in specialized printing equipment or complex software, while assemblers can rely on standard scanners to read the labels. |
However, the automotive industry also illustrates Code 39's limitations. As parts have become smaller and more densely packed, some applications have moved to higher-density symbologies such as Data Matrix for direct part marking. Nevertheless, Code 39 remains common for many categories of automotive parts where label space is not severely constrained. |
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4.3 Healthcare: Patient Safety and Device Identification |
The healthcare sector adopted Code 39 through the standards of the Health Industry Business Communications Council (HIBCC). HIBCC established labeling standards for medical devices, pharmaceuticals, and patient identification, aiming to improve patient safety through accurate tracking and identification. |
In hospitals, Code 39 barcodes appear on medication labels, patient wristbands, specimen containers, and medical equipment. The symbology's ability to encode alphanumeric data is critical---patient identifiers often combine letters and numbers, and medical device identifiers include manufacturer codes and model numbers. |
The healthcare environment presents unique challenges. Labels must be legible under various lighting conditions, resistant to moisture and alcohol, and scannable by both handheld scanners and bedside devices. Code 39's tolerance for moderate printing variations and its compatibility with a wide range of scanning equipment make it a practical choice. |
The self-checking property is particularly valuable in healthcare, where misreading a patient identifier or medication label could have serious consequences. While many healthcare applications also implement check digits for added safety, Code 39's inherent error resistance provides a baseline level of reliability. |
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4.4 Libraries: Inventory and Circulation |
Libraries were among the earliest adopters of barcode technology outside the industrial sector. Since the 1980s, libraries have used barcodes to track books, periodicals, and other materials through circulation, inventory, and interlibrary loan systems. |
Code 39 is a common choice for library barcodes. Library identifiers are typically numeric or alphanumeric, fitting comfortably within Code 39's character set. The symbology's simplicity makes it easy for libraries to generate their own barcodes using desktop printers and barcode fonts, without requiring specialized equipment or outside vendors. |
The density limitations of Code 39 are generally acceptable in libraries because books and media are not extremely small. The barcode is typically printed on a card or label of sufficient size to accommodate the symbology's length. For libraries with existing Code 39 systems, the barrier to switching to a newer symbology is high, given the investment in scanners, label stock, and integrated library systems. |
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4.5 Manufacturing: Work-in-Process Tracking |
In manufacturing, Code 39 is often used for work-in-process (WIP) tracking, where items move through multiple production stages and require identification at each step. Labels may be applied to parts, assemblies, storage bins, and production carts, containing information such as job numbers, order quantities, and routing instructions. |
The manufacturing environment is diverse, ranging from clean rooms to heavy industrial settings. Code 39 labels must be durable enough to withstand oil, chemicals, and abrasion in some settings, while remaining scannable under various lighting conditions. The symbology's robustness and compatibility with standard industrial scanners support these requirements. |
Manufacturers often use Code 39 for internal tracking purposes where labels are not required to conform to external standards. In such applications, the ease of implementation and the lack of mandatory check digits simplify system integration. A production supervisor can print Code 39 labels on demand using a standard label printer, assign them to work orders or parts, and scan them at each stage of production to update the manufacturing execution system. |
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4.6 Electronics and High-Tech Manufacturing |
The electronics industry presents contrasting requirements for barcode use. On one hand, components are often very small, making high-density symbologies such as Data Matrix or Code 128 more suitable for direct part marking. On the other hand, larger items such as circuit boards, enclosures, and finished devices frequently use Code 39 labels for tracking through assembly and testing. |
Code 39's alphanumeric capacity is valuable in electronics, where part numbers often include a mix of letters and numbers. The symbology is also compatible with the electrostatic discharge (ESD) safe materials and processes common in electronics manufacturing. |
The density issue, however, is a significant consideration. Electronics components are increasingly miniaturized, and the available label space for barcodes is shrinking. As a result, many electronics manufacturers have moved toward Code 128 or 2D symbologies for small parts, while retaining Code 39 for larger assemblies and shipping labels. |
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5. A Detailed Summary: Code 39's Technical Impact on Industry |
Now that we have surveyed Code 39's applications across multiple industries, we can synthesize the relationship between its technical characteristics and its practical use. The following summary provides a comprehensive view of how the symbology's features drive its adoption and shape its role. |
5.1 Alphanumeric Capacity: The Foundation of Versatility |
Code 39's ability to encode both letters and numbers was groundbreaking in 1974. Prior to its introduction, most barcode symbologies were numeric-only, limiting their utility for applications requiring alphanumeric identifiers. Code 39 opened the door to a new class of applications: asset tags, part numbers, work order identifiers, and other codes that combine letters and digits. |
In government property management, asset identifiers often include agency prefixes (e.g., 'GSA' or 'NAVY'), item category codes, and serial numbers. Code 39 can encode these directly, without requiring lookup tables or translation between numeric barcode values and alphanumeric meanings. |
The limitation to uppercase letters and a limited set of special characters is a constraint in some applications, but it is rarely problematic in inventory contexts. Asset identifiers, part numbers, and location codes are typically designed to use uppercase letters and digits, avoiding lowercase or obscure special characters. For applications requiring full ASCII support, the Extended Code 39 variant exists, albeit at the cost of density. |
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5.2 Self-Checking: Reliability Without Complexity |
The self-checking property of Code 39 provides a level of error resistance that is often sufficient for industrial and commercial applications. This property is particularly valuable in environments where labels may be scratched, dirty, or partially damaged, or where printing quality is not consistently high. |
For the GSA, this means that auditors can confidently scan asset tags that have experienced normal wear from years of use. A desk label that has been scraped by cleaning equipment or a computer tag that has faded from exposure to sunlight may still be scannable, reducing the need for frequent label replacement. |
The self-checking property also eliminates the mandatory requirement for a check digit. While check digits are recommended for critical applications---and mandated by some specifications such as MIL-STD-130---their absence simplifies system implementation. Organizations can generate and print Code 39 labels using basic tools without calculating check digits or validating them on scanning. |
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5.3 Low Data Density: The Defining Limitation |
Code 39's low data density is its most significant practical limitation. The symbology requires more horizontal space than Code 128 or 2D symbologies for the same data. This means that Code 39 is not suitable for very small items, labels with limited space, or applications requiring long identifiers. |
The density limitation affects the choice of symbology across industries: |
- In government property management, many tagged items are large enough---furniture, IT equipment, vehicles---that label space is not a major constraint. Code 39's density is acceptable in this context. |
- In automotive manufacturing, parts vary widely in size, and Code 39 is used where space permits. However, the density limitation has driven the adoption of Data Matrix for direct part marking on small components. |
- In electronics, the miniaturization trend has reduced label space, leading many manufacturers to shift away from Code 39 for small components. |
- In libraries, books provide sufficient surface area for Code 39 labels, and the density limitation is rarely a concern. |
- In healthcare, labels are often placed on packaging or equipment with adequate space, though the density issue has encouraged the use of Code 128 or 2D symbologies for some applications. |
The density limitation also affects the practical length of Code 39 identifiers. While Code 39 has no theoretical maximum length, longer identifiers produce proportionally longer barcodes that become difficult to print and scan. Practical implementations typically limit identifiers to 20-50 characters. |
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5.4 Wide Scanner Compatibility: The Legacy Advantage |
Code 39 enjoys near-universal support among barcode scanners. Nearly every linear imager and laser scanner sold in the past three decades includes Code 39 decoding as a default capability. This compatibility reduces implementation costs and simplifies system integration. |
For the GSA, this means that any standard scanner can read Code 39 asset tags, regardless of manufacturer or age. Federal agencies can purchase scanners from multiple vendors without worrying about Code 39 compatibility. Similarly, software systems that include barcode scanning support are virtually guaranteed to handle Code 39. |
For the automotive industry, Code 39's compatibility is a significant advantage in a supply chain with thousands of suppliers using different equipment. A supplier can generate Code 39 labels using a simple barcode font, and the assembler can read those labels with standard scanners, without requiring specialized hardware or software. |
For libraries, Code 39 compatibility with standard scanners enables the use of off-the-shelf equipment for circulation and inventory tasks. |
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5.5 Simplicity of Implementation: Low Barrier to Entry |
Code 39's simplicity is perhaps its most attractive feature for many organizations. Because no check digit is required for basic operation, generating Code 39 barcodes can be as simple as selecting a Code 39 font, typing the data between asterisks, and printing. This low barrier to entry has made Code 39 accessible to organizations of all sizes, from small libraries to large government agencies. |
The simplicity extends to scanning as well. Code 39 readers typically do not require configuration for data format or check digit handling in basic installations. The scanner reads the barcode and outputs the data between the start and stop asterisks, with minimal processing. |
However, this simplicity comes with trade-offs. Without a check digit, the system relies solely on Code 39's self-checking property for error detection. In practice, this is often sufficient, but critical applications should implement the optional Modulo 43 check digit for added safety. |
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5.6 The Extended Variant: Addressing the ASCII Limitation |
For applications requiring lowercase letters or the full ASCII character set, Code 39 Extended (also called Full ASCII Code 39) provides a workaround. By using pairs of standard Code 39 characters to represent each extended character, the variant can encode all 128 ASCII characters. |
The trade-off is density---each extended character requires two standard characters, effectively doubling the length of the barcode for the affected characters. For this reason, Code 39 Extended is used selectively, typically in applications where the barcode data includes occasional lowercase letters or special characters that cannot be avoided. |
In practice, most inventory and asset tracking applications avoid the need for Code 39 Extended by designing identifiers using uppercase letters and digits. For those applications that require full ASCII, Code 128 is often a better choice, offering higher density and native full ASCII support. |
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6. Conclusion: The Enduring Role of Code 39 |
Code 39 has survived for more than five decades in a field characterized by rapid technological change. Its persistence is not due to accident or inertia alone, but to a specific set of technical characteristics that remain relevant for a large class of applications. |
The symbology's alphanumeric capacity, self-checking property, wide scanner compatibility, and ease of implementation make it well-suited to inventory and asset tracking across government, defense, automotive, healthcare, libraries, and manufacturing. These industries value reliability, simplicity, and low implementation costs over the highest possible data density or the latest features. |
At the same time, Code 39's limitations are real and significant. Its low data density makes it unsuitable for small items, dense packaging, or applications with very long identifiers. Its limited character set (uppercase only in the standard variant) requires workarounds for lowercase or extended ASCII data. For these reasons, newer symbologies such as Code 128 and Data Matrix have displaced Code 39 in many applications where density or character support is paramount. |
For the GSA, Code 39 represents a pragmatic choice. Office furniture and IT equipment are not small items, their identifiers are typically short and alphanumeric, and the existing infrastructure already supports Code 39 scanning. The symbology works reliably for asset inventory audits, and the cost of migrating to a different symbology would outweigh the benefits. The GSA's continued use of Code 39 is therefore not an anachronism but a reflection of a mature technology that remains adequate for its intended purpose. |
For organizations considering Code 39 for new implementations, the decision should be based on a careful assessment of requirements. If label space is generous, if identifiers are alphanumeric but not too long, if scanner compatibility is paramount, and if simplicity of implementation is a priority, Code 39 remains an excellent choice. If data density is critical, if full ASCII support is required, or if labels must fit on very small items, other symbologies may be more appropriate. |
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The technical characteristics of Code 39 are not merely academic details---they directly influence the success and cost of real-world applications. Understanding these characteristics enables informed decisions about when to use Code 39 and when to choose alternatives. As this chapter has shown, Code 39 continues to serve as a reliable workhorse in government property management and many other industrial applications, demonstrating that older technologies can remain relevant when they fit their niche well. |
cs@easiersoft.com