Conformance Testing and Certification Model for W3C Specifications

W3C Working Draft 2 January 2002

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This is the first draft from the W3C QA Activity.
It it based on a NIST White Paper entitled: Conformance Testing and Certification Model for Software Specifications, by Lynne Rosenthal, Mark Skall, and Lisa Carnahan
Daniel Dardailler (danield@w3.org)


The use of conformity assessment as a means by which buyers and sellers can communicate requirements will increase as information technology systems and applications grow more complex. Models for conformance testing and certification programs are necessary to understand principles and issues that are essential for successful conformity assessment programs. This paper presents one such model by identifying key roles, activities and products involved in any conformance testing and certification program. This model has been successfully used by NIST in helping private-sector organizations establish their certification programs.

Status of this document

This document is a Note, made available by the W3C Quality Assurance Activity (QAA) for discussion on the QA email discussion list. It is submitted as to stimulate discussion within the W3C Quality Assurance Interest Group regarding guidance to external organizations that may wish to establish certification programs.

It may form the basis of a W3C Note and as such may be modified, replaced or obsoleted by other documents. Publication of this document does not imply endorsement by the W3C, its membership or its staff. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". Please send comments on the publicly archived list www-qa@w3.org.

Table of Content

1. Introduction

2. Conformance Testing and Certification Model

3. Roles

4. Activities

5. Products

6. Examples

7. Conclusion


1. Introduction

As the pervasiveness of information technology increases, so does the importance of ensuring the quality of products (i.e., software and systems). Conformance testing is defined in ISO/IEC Guide 2, "as any activity concerned with determining directly or indirectly that relevant requirements are fulfilled". The W3C QA activity's goal is to make sure that all W3C specifications are covered by adequate tools supporting their conformance testing, but it is not chartered, nor is the W3C itself, to run certification program. The QA activity on the other hand is interested in understanding principles and issues that are essential for the development of successful conformity assessment programs run externally to W3C. The goal of this document is to describe a model by identifying key roles, activities and products involved in any conformance testing and certification program.

Communication between Buyers and Sellers

In the marketplace, conformance testing provides a vehicle for exchanging information between buyer and seller. It increases a buyer's (and/or user's) confidence in a product and its ability to meet their needs. It provides an independent, objective method for evaluating products and not becoming locked-into a single vendor. For sellers (and developers), conformance testing can help to substantiate claims that a product meets the given specification.

Conformance testing is a means of measuring whether a product faithfully implements a specification. The level and formality of the testing are determined by the market - the requirements of the buyer directly or an organization acting on behalf of a community of buyers, or by regulation (e.g., safety, health, national security concerns). For example, some programs may require a very formal testing and certification approach consisting of independent (i.e., third party), nationally accredited testing laboratories while others may be more appropriate for self declaration and demonstration testing.

The sections below describe a generic model for establishing a conformance testing and certification program. It describes the processes and procedures for establishing, administering a testing program. While much has changed regarding conformity assessment given the growth and changes in the software industry, the conformance and certification model has not. Examples are used to describe how the model is applied to support the changes in the software industr

2. Conformance Testing and Certification Model

It is well recognized that conformance testing and certification is a way to ensure that "standard-based" products are implemented. The advantage afforded by testing and certification are fairly obvious: quality products, competitive markets with more choices, commodity pricing, and less opportunity to become "locked in" to a particular vendor. Moreover, a testing and certification program based on well understood and sound principles will be acceptable and credible to its community of users.

The conformance testing and certification model described herein contains the fundamental roles, activities, and products that are necessary in administering and operating a testing and certification program (see Table 1). By adjusting and modifying the various activities, roles and products, the model can be applied and used in establishing any testing and certification program. Figure 1 highlights the interactions between the roles and activities. The model allows for roles, activities and/or products to be consolidated or further partitioned.

Roles Activities Products
Buyer Require Certification Specification
Seller Test Implementation Implementation Under Test (IUT)
Test Laboratory (TL) Recognize Test Method Test Method
Certificate Issuer Recognize Tester Test Report
Control Board (CB) Validate Results Certification Program Policy
Anser Programmatic Queries Testing Laboratory Criteria
Answer Test Method Queries Certificate of Conformance
Resolve Test Method Disputes
Validate Conformance
Issue Certificate
Table 1: Roles, Activities, and Products

Interaction among roles and activities
Figure 1: Interaction Among Roles and Activities

While actual testing and certification can be carried out by various organizations, it is essential that there be a centralized sponsor or owner of the testing and certification program. The sponsor has a fundamental interest in ensuring the success of the program. Typically, the sponsor establishes and maintains the conformance testing and certification program. It assumes responsibility for insuring that the components of the program are in place and becomes the centralized source for information about the program. The sponsor may be composed of one or more organizations. Examples of sponsors are consortia, trade associations, standards groups, or a government agency. More often than not, the sponsor of the program is also the Certificate Issuer.

3. Roles

To execute the activities of the model, five roles are defined. In the realization of this model, some roles may be combined and performed by a single organization or further distributed among several organizations.


The Buyer requires that a product be tested for conformance. The buyer uses the results of the testing to verify that a seller provides a product that conforms to the specification and meet procurement requirements. In general, the buyer is the impetus for sellers to undergo conformance testing. Specifically, if buyers don't demand that a product be tested and show evidence of that testing, it is most likely that sellers will not undertake having their products tested.


The Seller or developer uses the conformance tests and undergoes testing to demonstrate that the product adheres to the specification and thus, meets established conformance requirements. Additionally, developers may use the tests to debug their products prior to market

Test Laboratory

The Test Laboratory (TL) conducts the conformance testing using the prescribed test method. The testing is performed on the seller/developer's product. A TL can be an organization or individual. A TL can be accredited from a formal accreditation organization such as NIST's National Voluntary Laboratory Accreditation Program (NVLAP) or recognized by the buyer, seller, and certificate issuer, as qualified to perform the testing.

Certificate Issuer

The Certificate Issuer (CI) is responsible for issuing certificates for conforming products. The decision to issue a certificate is based on the testing results and established criteria for issuing certificates

Control Board

The Control Board (CB) is an impartial body of experts who function on behalf of the CI. The CB is responsible for resolving queries and disputes related to the testing process.

4. Activities

The activities comprising the model can be categorized into one of four areas:

Recognition of Competent Testing Laboratory

A Testing Laboratory (TL) is an entity that provides services to measure, examine, test, or otherwise assess conformance of an implementation with its specification. Within the buyer/seller model, a TL can be either a first-party, (the seller performs the testing), second-party (the buyer performs the testing), or third-party (an independent organization performs the testing) testing organization. All three types of testing are used in the software industry. Often there will be multiple TLs for a conformance testing and certification program

The Certificate Issuer (CI) as well as Sellers and other interested parties, must have confidence in the competency of the TL. Competence is based on three concepts,

  1. the ability to apply the test method correctly,
  2. the ability to repeat a given test and generate the same results,
  3. the ability to operate the TL in a manner that maintains objectivity and neutrality (obviously, first and second party testing organizations are not neutral).

The CI defines competence through requirements and criteria. The CI can then apply the criteria to a TL, determine its level of competency and, if appropriate, recognize the TL as competent to perform testing. This practical approach to identifying and recognizing qualified testing organizations is appropriate when costs, time and efforts do not warrant seeking accreditation from a formal accreditation organization.

If a more formal and rigorous approach is appropriate, there exists many accreditation bodies exist that are capable of performing this function. The National Voluntary Laboratory Accreditation Program (NVLAP) is a NIST organization that accredits testing organizations based on the requirements of ISO Guide 17025 and additional subject-matter requirements.

The purpose of the recognition criteria or accreditation is to assure that TLs are capable and competent to meet the needs of the testing and certification program. The basic activities to make this determination include:

Additional attributes required of a third-party TL include that it:

Testing with an Approved Test Method

For a Certificate of Conformance to be meaningful, all implementations must be tested in the same manner. Testing reflects the essence of technical requirements of specifications and measures whether a product faithfully implements the specification. A test method is a defined technical procedure for performing a test. A test is the technical operation that consists of the determination of one or more characteristics of a given product, process or service according to a specified procedure. A test suite is the collection of tests. Critical to the success of any conformance testing and certification program is an appropriate and adequate test method.

An adequate test method is one that provides test results that give enough information for the CI to be satisfied that conformance can be measured. An adequate test method meets the requirement of rigor. An appropriate test method is one that, while adequate, does not place undue requirements on the IUT and is cost justifiable. If the test method is too expensive to employ then it will not be used. The definition of adequate and appropriate is left to the CI to determine.

Testing Process

The Testing Process is described in a conformance testing and certification policy and procedures document. The document identifies the administrative as well as testing processes.

The testing process initiates with a seller (or anyone desiring to be tested) contracting with the TL to have an implementation tested for conformance. The seller and TL negotiate the scope of testing, the cost of testing, and the timeliness of testing. For a given seller, the TL must not be in a position to benefit nor suffer (beyond the testing fees) from the resulting pass or failure of the implementation under test (IUT).

Using the approved Test Method, the TL tests the IUT for conformance and reports the results in a Test Report. The TL forwards the Test Report and an indication of pass/fail to the CI. If the IUT successfully completes all the tests and meets the criteria for issuing certificates, the CI issues a Certificate of Conformanceto the seller. Typically, the CI maintains and makes available to the public, a listing of products that have received certificates of conformance.

Resolution of Queries and Disputes

Queries and disputes involving the test method, procedures, test results, and program administration are directed to the Control Board (CB). The purpose of the CB is to resolve these issues and communicate the decision to all parties involved. The CB acts on behalf of the CI. A query or dispute can be initiated by a seller, TL or entity (e.g., developer) at any point in the testing process. Queries and disputes should contain a statement of the problem, rationale for dispute, and desired resolution. All matters to be resolved by the CB should be determined by consensus or as determined by documented CB policy and procedures.

Additional activities that may be under the auspices of the CB include:

5. Products

The following products are used in the model:

Certification Program Policy

The Certification Program Policy (CPP) defines the certification system. ISO/IEC Guide 2 defines a certification system as a system having its own rules of procedure and management for carrying out conformity certifications. The CPP addresses the following:

Test Laboratory Criteria

Testing Laboratory Criteria serves three purposes. The first purpose is to define the competence and quality-related requirements that a testing laboratory must possess to be designated as a recognized testing laboratory. The second purpose is to describe the manner in which the laboratory will be assessed against the requirements. The third purpose is to show those who want to use the testing laboratory (e.g., sellers), or those who want to accept the conformance certificate as evidence of conformance (e.g., buyers) the rigor under which the testing laboratory operates


First and foremost to conformance testing and certification is the specification. This paper delineates "standards-based" software specification from other types of specification. This is because not all specifications can be objectively tested for conformance. We recognize that not all "standards-based" specifications can be objectively tested. However objective measurement (not necessarily conformance testing per se) is usually a goal in these specification development efforts

If the specification can not be objectively tested, then a alternate approach to conformance testing should be used to measure whether a produce faithfully implements the specification. This is because an accepted test method cannot be developed, thus repeatability and reproducibility cannot be ensured.

Implementation Under Test

The implementation under test (IUT) is the object that is being tested for conformance. For software specifications it is the software that has implemented the specification. For any certification program, the scope of the IUT must be defined and delineated from the rest of the supporting software and hardware of the total system (referred to as the system under test). In many current certification programs the hardware that is used by the software must also be defined. The software and supporting hardware constitute the IUT and are listed in both the test report and certificate of conformance.

Test Method

The test method must be adequate and appropriate within the conformance testing and certification program in which it is used. Beyond these properties, test methods (and thus the tests) should be objective, have adequate coverage, and correctly implement the specification. In trying to meet these requirements, those using and applying the test method should not make the common mistake of allowing the test method to become the specification. This means that sellers (builders of IUTs) will build the IUT to pass the conformance tests, rather than building to the specification.

An objective test method allows for test results to be reproducable by the same testing laboratory and to be repeatable by a different laboratory. Initially some test methods do not quite achieve a sufficient level of objectivity. However objectivity should be something that is always strived for in the development and ongoing refinement of a test method.

Test Report

A test report contains the results of the testing effort, along with any additional information required by the CI. The test report should provide enough information that, if necessary, the testing effort could be duplicated. The testing report should contain:

Certificate of Conformance

The certificate of conformance is typically a summation of the test report. Since it is often used in the procurement process, it includes information most pertinent between the busyer and the seller.

The certificate includes statements made by the CI. These statements articulate what the CI is asserting as being conformant. Typically these statements indicate that "this IUT was tested in this environment, on this day, using this test method: the test results produced were consistent with expected test results". The certificate also includes the signature of a CI official.

6. Examples

ATA Computer Graphics Metafile (CGM) Conformance Testing Program

The Air Transport Association (ATA) CGM Program was originally established and operated by NIST to support the ATA 2100 Specification, Graphics Exchange (a.k.a. ATA CGM profile). The testing program is a critical component of the ATA's program to represent maintenance manuals in digital form and move to completely on-line maintenance manuals. Testing is done to ensure that the fidelity and quality of the digital information is sufficient to satisfy the airline companies' safety and quality concerns. The program is a means whereby a seller of a CGM implementation can formally demonstrate conformance to the ATA CGM profile.

NIST is currently working with the ATA in its assumption of the testing program. The ATA CGM Conformance Testing Program will consist of recognized Testing Laboratories to conduct the testing and a Control Board to handle disputes and serve as an advisor to the ATA. The ATA will act as the sponsor and administrator of the program. The ATA or an ATA designate will issue certificates of conformance. The roles, activities, and products as described in the generic model apply here with little modification. The Control Board takes on the additional activity of assessing the testing laboratories according to pre-established criteria. Additionally, the ATA Technical Information Communication Committee's Graphics Working Group serves as a technical advisor to both the ATA and the control board.

The test method consists of a NIST developed test suite and test procedures. The test method has been accepted and used by the community. It is publicly available along with other program documents.

IEEE POSIX Validation Service

The IEEE established a validation service for the POSIX (Portable Operating System Interface). The IEEE Validation Service uses accredited POSIX testing laboratories, issue certification of validated test results, and maintains a register of accredited laboratories and successfully tested products. The laboratories are accredited by the NVLAP under its POSIX program

The requirement for testing is buyer driven. Initially, federal agencies in their requests for procurement (RFP) of POSIX systems required certificates of validation prior to purchase. However, the benefits of POSIX testing and its acceptance in the industry has resulted in sellers requesting to be tested as a matter of course, rather than a procurement requirement.

The test suite was produced in a joint effort between NIST and several computer vendors. The original testing policy and procedures produced by NIST have been adopted by the IEEE.

7. Conclusion

This model describing the conformance testing and certification process has been used many times over in certification programs for standards-based software specifications. The examples above illustrate just a few of these programs. It will continue to be used as a communication mechanism between buyers and sellers.

Test method developers must continue to develop test methods that have adequate coverage with regard to the specification; are well defined in terms measurement (i.e., what does each test case prove); and be adequate and appropriate as defined by the Certificate Issuer.

As the industry moves toward component based software, the challenge will be to develop test methods and associated certification programs that can provide meaningful measurement in this environment


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