| |
| |
Uniformity of structure, of style, and of terminology shall be maintained not only within each standard, but also within a series of associated standards. The structure of associated standards and the numbering of their clauses shall be identical, as far as possible. Analogous wording shall be used to express analogous provisions; identical wording shall be used to express identical provisions.
The same term shall be used throughout each standard or series of standards to designate a given concept. The use of an alternative term (synonym) for a concept already defined shall be avoided. As far as possible, only one meaning shall be attributed to each term used.
The word shall is used to indicate mandatory requirements strictly to be followed in order to conform to the standard and from which no deviation is permitted (shall equals is required to). The use of the word must is deprecated and shall not be used when stating mandatory requirements; must is used only to describe unavoidable situations. The use of the word will is deprecated and shall not be used when stating mandatory requirements; will is only used in statements of fact.
The word should is used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others; or that a certain course of action is preferred but not necessarily required; or that (in the negative form) a certain course of action is deprecated but not prohibited (should equals is recommended that).
The word may is used to indicate a course of action permissible within the limits of the standard (may equals is permitted to).
The word can is used for statements of possibility and capability, whether material, physical, or causal (can equals is able to).
The words that and which are commonly misused; they are not interchangeable. That is best reserved in essential (or restrictive) clauses; which is appropriate in nonessential (or nonrestrictive), parenthetical clauses. Simply stated, if a comma can be inserted before the word that or which, the word should be which. If a comma would not be used, the word to use is that.
In order to reflect the changing practices in language usage, the IEEE Standards Department uses, in as many cases as possible, generic titles (such as chair rather than chairman) in the body of the standard. The following practices shall apply:
Generally, it is preferable to avoid the use of the word safe in a standard unless the condition or practice referenced by the word safe has been tested under all cases as being, in fact, safe. Typically, this is not the case. Thus, unless it can be demonstrated that such condition or practice is safe, it should not be used. Words such as safer or safest can be used in a relative context if it can be demonstrated to be the case. For example, it is proper to say that one set of conditions or practices is safer than another, if in fact true, or that it is safer to employ a certain practice than not in a given situation. However, the term safest implies an absolute condition, which, in certain contexts, has the same implication as safe and, thus, should not be used. For example, this is the safest set of conditions for using waveguide is an improper usage.
The word safety should be avoided if it is being used to address a set of conditions or practices that have not been established for the purpose of promoting safety under all situations in which such conditions or practices will be employed. For example, the following 10 safety considerations should be reviewed before implementing this practice should not be used.
The first-person form of address (I, we) or the second-person form of address (you) should not be used or implied in standards, e.g., “You should avoid working on lines from which a shock or slip will tend to bring your body toward exposed wires.” This sentence should be rewritten to identify the addressee, as follows: “Employees should avoid working on lines from which a shock or slip will tend to bring their bodies toward exposed wires.”
Technical abbreviations and acronyms should be used to save time and space, but only if their meaning is unquestionably clear to the reader. The first use should be spelled out, followed by the abbreviation or acronym itself in parentheses. Exceptions to this are approved SI units. A list of abbreviations and acronyms may be included as a separate clause, if necessary (see 10.6). SI unit symbols are not abbreviations and shall not be included in a list of abbreviations and acronyms.
Abbreviations and acronyms should be avoided in titles of standards. However, if such use is warranted, the procedure stated in the previous paragraph shall be followed. Refer to IEEE Std 260.1, IEEE Std 260.4, and IEEE Std 280 for the style of presentation of abbreviations.
In most cases, compound adjectives (such as fiber-optic cable, lead-acid batteries, power-operated valve assemblies) should be hyphenated. IEEE Standards project editors check documents for consistency of hyphenation; when the working group has a decided preference (such as life cycle process), that preference will be enforced. The use of hyphenated multiple adjectives (such as compressed-air-actuated power tools) should be limited to cases where such use is necessary to ensure comprehension.
The initial letter of the first word should be capitalized in
— Clause, subclause, and annex headings — Specific cross-references in text [e.g., Table 1, Figure 12, Note 2, Equation (3)] — Titles for figures — Titles for tables — Column and line headings in tables (see Table 2) — Lettered and numbered list entries
When using standard designations in text, two simple rules apply:
The word quantity has many meanings; in this clause the word refers to physical
quantities, which are measurable attributes such as length, mass, time, and
temperature. A unit is a particular sample of a quantity, chosen so that an
appropriate value may be specified. Meter, kilogram, hour, and degree Celsius
are some of the units used for the four quantities noted previously. The value
of a quantity is generally expressed as the product of a number and a unit.
Quantities and units may be represented in text by letter symbols, and are always
so represented in equations.
The following rules should be observed:
In 1995, the IEEE implemented a metric policy (IEEE Policy 9.19) that calls for measured and calculated values of quantities to be expressed in metric units [SI (Système International d’Unités)] in IEEE publications. (See IEEE/ASTM SI 10 for guidance on metric practice.) The IEEE-SA Standards Board Implementation Plan for the IEEE metric policy states that proposed new standards and revised standards submitted for approval should use metric units exclusively in the normative portions of the standard. Inchpound data may be included in parentheses after the metric unit if the sponsor believes that the audience for this document would benefit from the inclusion of inch-pound data, based on concerns for safety or clarity. Metric units shall always be the primary unit of measurement.
IEEE Policy 9.19 recognizes the need for some exceptions and contains the following statement: “Necessary exceptions to this policy, such as where a conflicting world industry practice exists, must be evaluated on an individual basis and approved by the responsible major board of the Institute for a specific period of time.” Standards Coordinating Committee 14, as part of the coordination process, shall review requests for individual exceptions, including those noted below, and shall report its recommendations to the IEEE-SA Standards Board.
For further information, see IEEE/ASTM SI 10, IEEE Std 260.1, and IEEE Std 270.
In IEEE standards letter symbols should be used rather than abbreviations. Letter symbols include symbols for physical quantities (quantity symbols) and symbols for the units in which those quantities are measured (unit symbols). Unlike common abbreviations, letter symbols are invariant in singular and plural, they are not followed by a period, and case is maintained independent of the surrounding text (see IEEE Std 260.1).
For example, standard quantity symbols for length, mass, time, and temperature
are l, m, t, and q. They are set in italic letters. Unit symbols for
the same four quantities are m, kg, s, and ºC, set in roman (upright) letters.
Note especially that V is the symbol for the unit “volt,” and V
(italic) is the symbol for the quantity “voltage.” Unit symbols may
not be used to stand for the quantity being measured; that is, do not write
-- “The km between the substations is 20,” but write instead, “The
distance between the substations is 20 km.”
-- “The amperes that flow into the ground,” but write instead, “The
current that flows into the ground.”
-- “Polarity shall be additive for all kVA transformers rated at 200,”
but write instead, “Polarity shall be additive for all transformers with
an apparent power rating of 200 kVA.”
Letter symbols for quantities are always written in sloping (slanted) type whether the surrounding text body is upright or italic. Note the distinction between sloping and italic type, especially for symbols such as a, a, g, g, and so forth.
Letter symbols for quantities shall comply with IEEE Std 280. When standards for letter symbols in particular fields have been established, they should be used. The same letter symbols should be used for the same quantity throughout a particular standard regardless of the units employed or of the special values assigned.
Quantities and quantity symbols should not be used as if they were units and unit symbols. Therefore, it is allowable to write 2g to indicate twice the value for g, but neither "two g's of acceleration" nor "a = 2 g".
Back to table
of contents 
Go
to next clause
 | |||
| |||
