Chapter 7
Types of Standards
7.1 Introduction
Standards are written differently depending on the culture of the organization developing them, the product or process they are defining, the capabilities of the organization implementing them, and other factors. There are numerous ways in which they can be categorized. Some of these were noted briefly in Chapter 1, and this chapter will address them in more detail. Some of these categorization approaches have been formalized in standards themselves, while some are used simply because they are helpful in understanding and approaching standards, whether for their use or their development. ISO/IEC Guide 2, Standardization and related activities – General Vocabulary, offers a number of useful ways of looking at standards, some of which are included in the following list.
7.2 Performance versus Prescriptive
7.2.1 Performance Standards
Performance standards are those that are written to define what must be accomplished. Writing a standard in this way allows the implementing organization a great deal of flexibility in how it chooses to comply. There are benefits to this approach, especially in those cases where the interfaces are minimal and what must be accomplished is easy to define. The risk is that not enough thought may be given to what is actually needed, and certain critical aspects of the product (process, etc.) may be left out of the standard. In this case, a fully compliant product may be produced and yet not fulfill what is truly needed.
Cases in which a performance standard may be particularly desirable include the following:
- The technology is not well developed, or is evolving, such that it is too early to be more prescriptive.
- What must be accomplished can be readily defined in sufficient detail.
- A number of viable ways of accomplishing the task exist, and no one of them clearly dominates the market.
- It is possible to adequately characterize any interfaces, or there are none.
For example, a standard for developing automobiles could be produced as a performance standard. It could be written in broad general terms as follows:
Construct a car that will carry four people in safe, quiet, efficient comfort.
Such requirements are all valid, but many more are needed. Carry them where and how far? How big are these people? How heavy? Do they have luggage? Is the car enclosed? Does it have seat belts? How safe is safe, and how do you achieve it? Quiet for the passengers, or for those in the surrounding environment? What does “efficient” mean? Is it made of a particular material? Does it have turn signals? The additional potential requirements go on and on.
Performance standards can be particularly useful when what must be accomplished is known, the ways of accomplishing the task have not been extensively examined and tested through experience, and there are not extensive interfaces or other restricting elements and requirements. They allow for flexibility and innovation. The challenge is often in determining and agreeing that their requirements have been met.
7.2.2 Prescriptive Standards
Prescriptive standards specify in detail what must be done. When the writer of the standard not only knows what must be accomplished, but also knows how it should be accomplished, then a prescriptive standard is likely to be appropriate. Most of the OSHA regulations are quite prescriptive. For example, in the section on overhead and gantry cranes they say things such as, “Fire extinguisher. Carbon tetrachloride extinguishers shall not be used,” and “If sufficient headroom is available on cab-operated cranes, a footwalk shall be provided on the drive side along the entire length of the bridge of all cranes having the trolley running on the top of the girders.” These are cases in which what is required can be clearly and unambiguously stated, and in which it makes sense to mandate consistency.
Aspects of a standard that might make a prescriptive standard desirable include the following:
- The field is well developed and it is not anticipated that the details specified would hamper innovation.
- What must be accomplished is understood and also how it is best accomplished.
- Processes have been well worked out and defined.
7.2.3 Component Standards
Component standards are the ultimate in “prescriptiveness.” They are used when the exact product required is known. They specify all the materials, dimensions, and other essential characteristics of the part, such that a component that meets the standard will work in the application, and will be completely interchangeable with all other such parts. Component standards define pipe sizes, bearings, flanges and fittings, electrical components, and many other essentials of daily life. These are the standards that allow one to go to the store and purchase a light bulb, having full confidence that upon returning home again he/she will be able to screw it into essentially any light fixture in the house, turn on the switch, and have light. A person can buy faucets that will fit the sink, and locksets for the doors, with similar confidence.
This type of standard is used
- when interfaces and interchangeability are well understood and are critical,
- when mass production is applied by multiple manufacturers whose parts must fit together.
If innovation is to occur in a situation such as this, it will likely either come in the form of incremental change or result in a new standard for other configurations that will fit together with each other. Thus a different light bulb interface would have a new standard, or section in an existing standard, to define the critical characteristics of that interface.
7.2.4 Hybrid Standards
Other than for component standards, it is very common to use a combination of performance and prescriptive requirements. This is practical when some aspects of a product or process are, or can be, very well defined, while others remain open.
Returning to the example of the automobile above, certain aspects are “nonnegotiables,” while others are left entirely to the designer. Antilock brakes are required, but the details of the design are not fully defined by regulation. Many specific components are purchased to component standards, others are designed to prescriptive standards, and some aspects of the design are left almost entirely up to the engineer. This hybrid approach tries to take advantage of the strengths of each type of requirement, while minimizing the risks and drawbacks.
Similarly, the AIAA standard for composite overwrapped pressure vessels is very specific about some things such as safety factors and acceptance requirements, but it allows flexibility in how stress analyses are performed, something that in the ASME BPVC is fairly tightly defined in most cases.
Hybrid standards are often preferred because their use permits a great deal of specificity when needed while retaining the advantages of performance standards for other aspects of a product.
7.3 Geographical, Political, or Economic Extent
It is sometimes useful to categorize standards on the basis of the extent of their influence. ISO/IEC Guide 2, Standardization and related activities – General Vocabulary, offers the following categories to describe the extent of influence of various standards.
- International Standardization: Standardization in which involvement is open to relevant bodies from all countries.
- Regional Standardization: Standardization in which involvement is open to relevant bodies from countries from only one geographical, political, or economic area of the world.
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National Standardization: Standardization that takes place at the level of one specific country.
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Note: Within a country or a territorial division of a country, standardization may also take place on a branch or sectoral basis (e.g., ministries), at local levels, at association and company levels in industry, and in individual factories, workshops, and offices.
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Provincial Standardization: Standardization that takes place at the level of a territorial division of a country.
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Note: Within a country or a territorial division of a country, standardization may also take place on a branch or sectoral basis (e.g., ministries), at local levels, at association and company levels in industry, and in individual factories, workshops, and offices.
7.4 Mandatory or Voluntary
As previously noted, compliance with some standards is mandatory while that with others is voluntary. This book uses the term “jurisdictional standard” to refer to those standards that are mandatory and “voluntary consensus standard (VCS)” for those that are voluntary. Again, in some cases jurisdictional standards will make use of incorporation by reference to require compliance with certain otherwise voluntary standards. This practice is addressed in more detail in Chapter 5.
7.5 Consensus versus Nonconsensus
Interest groups and large companies often develop their own standards. While these must conform to the well-established national and international standards if compliance with them is required or claimed, certain process details necessary for use or production often remain proprietary. These details often deal with procedures and guidelines for design, manufacturing, testing, documenting, and quality control. As such, they are part of the closely guarded intellectual property (IP) that keeps a company competitive.
These standards typically do not meet the ANSI requirements for VCSs (one exception is UL, which does publish VCS). The distinctions among these categories are discussed in more detail in Chapters 3–5.
7.6 Purpose
There are many categories that describe various purposes of standards. Among these are fitness for purpose, quality, compatibility, interchangeability, and safety. A number of other categories could be identified as well. Classifying standards in this way can be helpful, but often a single standard will address more than one of these issues. Still, this classification approach can be particularly useful in deciding where to draw the lines between two or more standards.
As an example, ASTM A-269, Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service, includes only a small part of the total requirements for this product. It references five other ASTM standards covering such topics as practices for detecting susceptibility to intergranular attack, requirements for plate, sheet, and strip that are used to make welded tubes, and general requirements for tubes. By breaking down the requirements in this way, a great deal of redundancy is avoided, since the referenced standards are also referenced by many other higher level standards.
7.7 Subject
Looking at standards from a subject perspective, such as testing, product, process, service, interface, and data to be provided, gives another view. This approach can be helpful in making certain that a standard has addressed everything it should, whether internally or by reference. It can also simplify the process of identifying applicable standards for various parts of an operation.
7.8 Surprise Consequences of a Successful Standard
The importance of standards can be illustrated by the case of IBM's entry into and exit from the personal computer market. IBM, a large computer company up to that point mostly interested in the main frame computer market, decided to join the personal computer market in 1981 by introducing its own computer. It also decided to use off-the-shelf electronic components with a modular design. The breakthrough in the personal computers came when this large computer company threw its weight behind the development of the back plane bus architecture standard that independent vendors could use to interface their product to the CPU. These products included the RAM, video card, sound card, hard drives, modem and Ethernet cards for communications, A/D and D/A converters for industrial control, and other internal devices.
Externally, user interface devices such as keyboard, mouse, touch pad and joystick, and other peripherals such as printers would interface through the standard serial and parallel ports. The only part that IBM made proprietary was the BIOS (basic input/output system). This was later developed by other vendors and made compatible with the IBM design, making it possible for other PC compatible (clones) to be manufactured by other companies, becoming the de facto, and ultimately the actual, standard. So successful and popular was this open bus architecture that when IBM introduced the more advanced but proprietary Micro Channel Architecture (MCA) in its personal system computers, it failed to secure sales and vendors refused to cooperate. In 2005, IBM sold its personal computer business to another company and exited the market.
An example of development of a component at first in the absence of standards, then with standards catching up is the Universal Serial Bus (USB) used in computers to communicate with various devices. Initially, computer manufacturers used only ports that were compatible with their own peripheral equipment in an effort to control the market. However, the explosion in the peripheral market, reinforced by consumer demand, forced the computer manufacturers to consider adapting ports to fit peripherals made by other manufacturers. Intel came up with a protocol framework for USB that allows various devices to send whatever data they desire. Acceptance of the USB was slow in the beginning when manufacturers were skeptical that they needed to accept it. When a USB was plugged in a computer a message would flash indicating “a driver is needed in order for this device to work.” However, as time went on, all of the operating systems (Windows, Mac, Linux, etc.) incorporated the needed drivers.
Initially, a small USB group was formed to develop a standard. Many companies joined the group later, once the benefits of USB became obvious. Today, it is rare to plug in a device and NOT have a driver available to transmit data. The data consists of a well-defined header packet that is standardized by a USB group. The group also standardized the physical dimensions, then the mechanical and electrical, and then the protocol level. The standard was revised many times over the years to take advantage of hardware and software changes that allowed for significantly greater data transmission speeds and to fend off competition from other interface protocols that were also evolving, with issues 1.0, 1.1, 2.0, 3.0, 3.1, and the current USB3.2. The current standard for the USB is over 600 pages long (www.usb.org).
The following is a partial list of topics of standards that have since been developed in the relatively new fields of computer hardware and software:
| Hardware | |
| ACPI | Advanced Configuration and Power Interface |
| AGP | Accelerated Graphics Port |
| ATX | Advanced Technology eXtended |
| DVI | Digital Visual Interface |
| EISA | Extended Industry Standard Architecture |
| Fire Wire | (IEEE 1394) |
| HDMI | High Definition Multimedia Interface |
| IDE | Integrated Drive Electronics. Extended to ATA/ATAPI |
| ISA | Industry Standard Architecture |
| PCI | Peripheral Component Interconnect |
| SATA | Serial ATA |
| SCSI | Small Computer System Interface |
| UDI | Unified Display Interface |
| USB | Universal Serial Bus |
| VESA | Video Electronics Standards Association |
| Software | |
| API | Applications Programming Interface |
| CGI | Common Gateway Interface |
| HTML | Hyper Text Markup Language |
| HTTP | Hypertext Transfer Protocol |
| MPI | Message Passing Interface |
| ODF | Open Document Format |
| Portable Document Format | |
| PNG | Portable Network Graphics |
| POSIX | Portable Operating System Interface (IEEE) |
| PS | Post Script |
| RTF | Rich Text Format |
| SQL | Structured Query Language |
| SVG | Scalable Vector Graphics |
| TWAIN | Technology Without An Interesting Name |
| UDF | Universal Disk Format |
| Unicode | Universal Code for text transfer |
| WAP | Wireless Application Protocol |
| WML | Wireless Markup Language |
| XML | Extensible Markup Language |
7.9 Summary
A number of approaches are used to categorize standards. Thinking about standards in this way can be helpful in determining how to structure a standard or group of standards, as well as ensuring their completeness. While it is not a topic of everyday discussion, understanding the various types of standards as looked at from different perspectives can also help in their effective use.
7.10 Case Study
Describe a standard that might have helped ease the transition to common use of the USB, discussed in Section 7.8, and identify performance and prescriptive aspects of such a standard.