Standardization News

Classifications, Practices and Guides

Over the course of the Rules&Regs column, we have discussed in detail three different types of ASTM International standards - test method, specification and terminology - and how these types are described in Form and Style for ASTM Standards. Of course, there are other types of standards, which are covered in Part C of Form and Style. In this column we will explore three standard types described in Part C-classifications, practices and guides.

C1.1 of Form and Style points out that the Regulations Governing ASTM Technical Committees defines a classification as "a systematic arrangement or division of materials, products, systems or services into groups based on similar characteristics such as origin, composition, properties or use."

In addition to mandatory sections that are the same for other standard types (title, designation, scope, significance and use, keywords), one other mandatory section exists, which is the most important part of a classification standard: basis for classification.

The basis for classification sets up categories in which groupings are made. Form and Style cites ASTM standard D388, Classification for Coals by Rank, as an example of a basis for classification. In this standard, higher rank coal is classified according to fixed carbon on a dry basis, while lower rank coals are classified according to caloric value on a moist basis.

Early in the introduction to Form and Style Part C, it is noted that when preparing to develop a standard, committees often question the differences between a practice and a guide, particularly since both types include many of the same sections. The most basic difference between the two is that a practice underscores a general usage principle whereas a guide suggests an approach.

According to C15.1, a practice is "an accepted procedure of one or more operations or functions." Practices may sometimes include one or more test methods that are necessary for the full use of the practice.

Examples of practices include those covering selection, preparation, application, inspection, necessary precautions for use or disposal, installation, maintenance and operation of testing apparatus.

A guide is defined in C15.2 as "a compendium of information or series of options that does not recommend a specific course of action." It is further stated that guides are developed to increase awareness of information and approaches in a given subject area. A series of options or instructions that offer direction without recommending a specific course of action is often proposed in a guide.

In addition to title, designation and keywords, mandatory sections of practices and guides include scope and significance and use. The scope includes any information relating to the purpose of the practice or guide and to what it applies, while significance and use includes information that explains the relevance and meaning of the standards.

In addition to the types of standards discussed here and in previous columns, Part C also includes reference radiographs, reference photographs, tables and charts as standard types. The form of these lesser used options is left to the jurisdiction of the sponsoring committee.