prEN IEC 60477-1:2021

Laboratory resistors - Part 1: Laboratory DC resistors

2021-11-10: BT decision (D170/C037) to permanatly remove the link to  LVD (M/511)

Gleichstrom-Meßwiderstände

Résistances de laboratoire - Partie 1: Résistances de laboratoire à courant continu

Laboratorijski upori za enosmerni tok

General Information

• Status: Not Published
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 31.040.01 - Resistors in general
• Technical Committee: CLC/TC 85X - Measuring equipment for electrical and electromagnetic quantities
• Drafting Committee: IEC/TC 85 - IEC_TC_85
• Current Stage: 4020 - Enquiry circulated
• Due Date: 21-May-2021
• Completion Date: 21-May-2021
• Directive: 2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Mandate: M/511 - Mandate to CEN, CENELEC and ETSI relating to harmonised standards in the field of the Low Voltage Directive
• Ref Project: oSIST prEN IEC 60477:2021 - Laboratory DC resistors

RELATIONS

• Revised: EN 60477:1997 - Laboratory d.c. resistors
• Effective Date: 10-Nov-2020
• Revised: EN 60477:1997/A1:1997 - Laboratory d.c. resistors
• Effective Date: 12-Oct-2021

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN IEC 60477:2021
01-julij-2021
Laboratorijski upori za enosmerni tok
Laboratory DC resistors
Gleichstrom-Meßwiderstände
Résistances de laboratoire à courant continu
Ta slovenski standard je istoveten z: prEN IEC 60477:2021
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
oSIST prEN IEC 60477:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60477:2021
85/771/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60477 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2021-05-21 2021-08-13
SUPERSEDES DOCUMENTS:
85/734/CD, 85/757/CC
IEC TC 85 : MEASURING EQUIPMENT FOR ELECTRICAL AND ELECTROMAGNETIC QUANTITIES
SECRETARIAT: SECRETARY:
China Ms Guiju HAN
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.

Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of

which they are aware and to provide supporting documentation.
TITLE:
Laboratory DC resistors
PROPOSED STABILITY DATE: 2025
NOTE FROM TC/SC OFFICERS:

Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.

You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without

permission in writing from IEC.
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2 CONTENTS

4 FOREWORD ...................................................................................................................... - 3 -

5 1 Scope ......................................................................................................................... - 5 -

6 2 Normative references ................................................................................................. - 5 -

7 3 Terms and definitions ................................................................................................. - 5 -

8 3.1 General terms .................................................................................................... - 5 -

9 3.2 Characteristic values ......................................................................................... - 8 -

10 3.3 Accuracy class, class index ............................................................................... - 9 -

11 3.4 Influence quantities, reference conditions, nominal range of use ........................ - 9 -

12 3.5 Uncertainty and variations ............................................................................... - 11 -

13 4 Classification ............................................................................................................ - 13 -

14 5 Limits of intrinsic uncertainty .................................................................................... - 13 -

15 5.1 General ............................................................................................................ - 13 -

16 5.2 Requirement for multiple resistor ..................................................................... - 14 -

17 6 Reference conditions ................................................................................................ - 14 -

18 7 Permissible variations............................................................................................... - 15 -

19 7.1 Limits of variation ............................................................................................ - 15 -

20 7.2 Conditions for the determination of the variations............................................. - 16 -

21 7.3 Influence of self-heating (power dissipation) .................................................... - 16 -

22 7.4 Influence of position ......................................................................................... - 16 -

23 8 Further electrical and mechanical requirements ........................................................ - 16 -

24 8.1 Electrical safety requirements .......................................................................... - 16 -

25 8.2 Insulation resistance ........................................................................................ - 16 -

26 8.3 storage and transport conditions ...................................................................... - 17 -

27 8.4 Terminal .......................................................................................................... - 17 -

28 8.5 Provision of temperature measuring facilities ................................................... - 17 -

29 8.6 Guarding and screening requirements .............................................................. - 17 -

30 9 Information, markings and symbols ........................................................................... - 17 -

31 9.1 Information ...................................................................................................... - 17 -

32 9.2 Markings, symbols and their locations .............................................................. - 18 -

33 9.3 Marking relating to the reference conditions and nominal ranges of use ........... - 18 -

34 Annex A (informative) Reference Information ................................................................. - 21 -

35 A.1 Thermoelectric effects (see Sub-clause 6.3, Note 2) ........................................ - 21 -

36 A.2 Reference range and nominal range of use ...................................................... - 21 -

37 A.3 Example of marking for a single resistor .......................................................... - 22 -

38 A.4 Example of marking for a five-dial resistor ....................................................... - 22 -

40 Figure A.1 – Effect of temperature ................................................................................... - 21 -

41 Figure A.2 – Example of marking for a single resistor ...................................................... - 22 -

42 Figure A.3 – Example of marking for a five-dial resistor ................................................... - 22 -

44 Table 1 – Limits of intrinsic relative uncertainty and limits of relative stability ................... - 14 -

45 Table 2 – Reference conditions and permissible range of influence quantities ................. - 15 -

46 Table 3 – Nominal range of use for influence quantities ................................................... - 15 -

47 Table 4 – Examples of markings for temperature ............................................................. - 19 -

48 Table 5 – Symbols for marking resistors .......................................................................... - 20 -

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51 INTERNATIONAL ELECTROTECHNICAL COMMISSION
52 ____________
54 LABORATORY DC RESISTORS
57 FOREWORD

58 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

59 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

60 international co-operation on all questions concerning standardization in the electrical and electronic fields. To

61 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

62 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

63 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

64 in the subject dealt with may participate in this preparatory work. International, governmental and non-

65 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

66 with the International Organization for Standardization (ISO) in accordance with conditions determined by

67 agreement between the two organizations.

68 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

69 consensus of opinion on the relevant subjects since each technical committee has representation from all

70 interested IEC National Committees.

71 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

72 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

73 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

74 misinterpretation by any end user.

75 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

76 transparently to the maximum extent possible in their national and regional publications. Any divergence

77 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

78 the latter.

79 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

80 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

81 services carried out by independent certification bodies.

82 6) All users should ensure that they have the latest edition of this publication.

83 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

84 members of its technical committees and IEC National Committees for any personal injury, property damage or

85 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

86 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

87 Publications.

88 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

89 indispensable for the correct application of this publication.

90 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

91 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

92 International Standard IEC 60477 has been prepared by IEC technical committee 85:

93 Measuring equipment for electromagnetic quantities.

94 This second edition cancels and replaces the first edition published in 1974, Amendment 1:

95 1997. This edition constitutes a technical revision.

96 This edition includes the following significant technical changes with respect to the previous

97 edition:
98 – replaced d.c. with DC according IEC 60050-151:2001, 151-15-02;
99 – extended the resistor accuracy class scope of this document;
100 – deleted the resistor accuracy class expression in parts per million (ppM);
101 – excluded the active resistor from scope of this document;
102 – updated the terms and definition according to new IEC 60050 series;

103 – changed the term “resistance decade” to “resistance dial” to cover the multi-dial resistors

104 with other resistance step values;
105 – updated the intrinsic error to intrinsic uncertainty according IEC 60359;

106 – added the limits of relative stability for resistor of classes 0.00005… 0.01;

107 – added the requirement of high voltage high resistor;
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108

109 – updated the safety symbols and requirements according to new IEC 61010 series;

110 – updated the insulation resistance requirements of resistor;
111 – added the requirement of temperature coefficient;

112 – updated the temperature requirements for transport and storage of resistor according to

113 IEC 60051-1.
114 The text of this International Standard is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
115

116 Full information on the voting for its approval can be found in the report on voting indicated in

117 the above table.

118 The language used for the development of this International Standard is English.

119 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

120 accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement,

121 available at www.iec.ch/members_experts/refdocs. The main document types developed by

122 IEC are described in greater detail at www.iec.ch/standardsdev/publications.

123 The committee has decided that the contents of this document will remain unchanged until the

124 stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

125 the specific document. At this date, the document will be
126 • reconfirmed,
127 • withdrawn,
128 • replaced by a revised edition, or
129 • amended.
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130
131 LABORATORY DC RESISTORS
132
133
134 1 Scope

135 This document applies to resistors intended for use as laboratory DC resistors (hereinafter

136 referred to as “resistors”) comprising standard resistors, single or multiple resistors of

137 accuracy Classes 0.00005…10 and single or multi-dial resistors of accuracy Classes

138 0.0005 … 10.
139 This document does not apply to:

140 a) resistors which are intended for use solely as permanent mounted circuit components,

141 b) resistors used on alternating current or on pulsed current,
142 c) active resistor

143 d) series resistors and shunts which are considered as accessories of electrical measuring

144 instruments in the relevant IEC publication.

145 EXAMPLE 1 IEC 60051: Recommendations for Direct Acting Indicting Electrical Instruments and Their

146 Accessories.

147 EXAMPLE 2 IEC 60258: Direct Recording Electrical Measuring Instruments and Their Accessories.

148
149 2 Normative references

150 The following documents are referred to in the text in such a way that some or all of their

151 content constitutes requirements of this document. For dated references, only the edition

152 cited applies. For undated references, the latest edition of the referenced document (including

153 any amendments) applies.
154 IEC 60027(all parts), Letter symbols to be used in electrical technology

155 IEC 60359: 2001, Electrical and electronic measurement equipment - Expression of

156 performance
157 IEC 60417, Graphical symbols for use on equipment

158 IEC 61010-1, Safety requirements for electrical equipment for measurement, control, and

159 laboratory use – Part1: General requirements

160 IEC 61010-2-30, Safety requirements for electrical equipment for measurement, control, and

161 laboratory use – Part 2-030: Particular requirements for testing and measuring circuits

162
163 3 Terms and definitions

164 For the purposes of this document, the following terms and definitions apply.

165 ISO and IEC maintain terminological databases for use in standardization at the following

166 addresses:
167 • IEC Electropedia: available at http://www.electropedia.org/
168 • ISO Online browsing platform: available at http://www.iso.org/obp
169 3.1 General terms
170 3.1.1
171 terminal

172 point of interconnection of an electric circuit element, an electric circuit or a network with

173 other electric circuit elements, electric circuits or networks

174 Note 1 to entry: For an electric circuit element the terminals are the points at which or between which the related

175 integral quantities are defined. At each terminal, there is only one electric current from outside into the element.

176 [SOURCE: IEC 60050-131:2002,131-11-11]
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177 3.1.2
178 two-terminal device

179 device having two terminals, or device having more than two terminals where only the

180 performance at two terminals forming a pair is of interest
181 [SOURCE: IEC 60050-151:2001, 151-12-13]
182 3.1.3
183 resistor
184 two-terminal device characterized essentially by its resistance
185 [SOURCE: IEC 60050-151:2001, 151-13-19]
186 3.1.4
187 four-terminal resistor
188 resistor fitted with two current terminals and two voltage terminals

189 [SOURCE: IEC 60050-313:2001, 313-09-06, modified – deleting the words “injection” and

190 “measuring”.]
191 3.1.5
192 single value resistor

193 device which provides a single definite resistance value between certain terminals

194 3.1.6
195 multiple value resistor

196 assembly comprising a number of resistors which are accessible either singly or in

197 combination and which provides definite resistance values between certain terminals

198 3.1.7
199 measuring dial

200 dial from which the value of the measured quantity is determined, taking into account the

201 range factor, if any

202 Note 1 to entry: In general, the dial also carries other information characterizing the instrument.

203 [SOURCE: IEC 60050-314:2001,314-09-03]
204 3.1.8
205 resistance dial

206 multiple resistor which, by means of a switching device, generally allows the selection of a

207 combination of resistance values rising in equal steps, each step corresponding to an

208 increment of a n-ary resistance value

209 Note 1 to entry: It is usual resistance decade with each step corresponding to an increment of a decadic

210 resistance value (e.g. 0.1 Ω or 1 Ω or 10 Ω...)

211 Note 2 to entry: A resistance decade generally allows a selection of 10, 11 or 12 resistance values (including

212 zero).
213 3.1.9
214 multi-dial resistor

215 multiple resistor comprising a number of resistance dials which are generally connected in

216 series

217 Note 1 to entry: For resistor comprising a number of resistance decades, It is usually called multi-decade resistor.

218 3.1.10
219 material measure

220 device intended to reproduce or supply, in a permanent manner during its use, one or more

221 known values of a given quantity
222 EXAMPLE Standard electric resistor
223 Note 1 to entry: The quantity concerned may be called the supplied quantity

224 Note 2 to entry: The definition covers also those devices, such as signal generators and standard voltage or

225 current generators, often referred to as supply instruments.

226 Note 3 to entry: The identification of the value and uncertainty of the supplied quantity is given by a number tied

227 to a unit of measurement or a code term, called the nominal value or marked value of the material measure.

228 [SOURCE: IEC 60359:2001, 3.2.3, modified – EXAMPLE has been added according IEC

229 60050-311:2001,311-03-03.]
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230 3.1.11
231 (measurement) standard

232 material measure, measuring instrument, reference material or measuring system intended to

233 define, represent physically, conserve or reproduce a unit of a quantity, or a multiple or sub-

234 multiple thereof (for example, standard resistance), or a known value of a quantity (for

235 example, standard cell), with a given uncertainty
236 [SOURCE: IEC 60050-311:2001, 311-04-01]
237 3.1.12
238 residual resistance

239 resistance value between the terminals of a multiple resistor having switching devices with a

240 zero position, when all switching elements are set to the zero position
241 3.1.13
242 screen
243 shield (US)

244 device intended to reduce the penetration of an electric, magnetic or electromagnetic field into

245 a given region
246 [SOURCE: IEC 60050-151: 2001, 151-13-09]
247 3.1.14
248 (local) earth
249 (local) ground (US)

250 part of the Earth which is in electric contact with an earth electrode and the electric potential

251 of which is not necessarily equal to zero
252 [SOURCE: IEC 60050-195:1998, 195-01-03]
253 3.1.15
254 earth(verb)
255 ground (verb) (US)

256 make an electric connection between a given point in a system or in an installation or in

257 equipment and a local earth
258 Note 1 to entry: The connection to local earth may be
259 – intentional, or
260 – unintentional or accidental
261 and may be permanent or temporary.
262 [SOURCE: IEC 60050-195:1998, 195-01-08]
263 3.1.16
264 earthing terminal
265 grounding terminal (US)
266 DEPRECATED: earth terminal

267 terminal provided on equipment or on a device and intended for the electric connection with

268 the earthing arrangement
269 [SOURCE: IEC 60050-195:1998, 195-02-31]
270 3.1.17
271 working voltage

272 highest RMS value of the AC or DC voltage across any particular insulation which can occur

273 when the equipment is supplied at rated voltage

274 Note 1 to entry: Transients and voltage fluctuations are not considered to be part of the working voltage.

275 Note 2 to entry: Both open-circuit conditions and normal operating conditions are taken into account.

276 [SOURCE: IEC 60050-581:2008, 581-21-19, modified – Note 1 and Note 2 to entry have

277 been added according to IEC 60010-1:2001 3.3.3.]
278 3.1.18
279 measurement category

280 classification of testing and measuring circuits according to the type of MAINS to which they

281 are intended to be connected
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282 Note 1 to entry: Measurement categories take into account overvoltage categories, short-circuit current levels,

283 the location in the building installation where the test or measurement is to be made, and some forms of energy

284 limitation or transient protection included in the building installation. See IEC 61010-2-30:2010 Annex AA for more

285 information.
286 [SOURCE: IEC 61010-2-30:2010 3.5.101]
287 3.1.19
288 insulation resistance

289 resistance under specified conditions between two conductive bodies separated by the

290 insulating material
291 [SOURCE: IEC 60050-151:2001, 151-15-43]
292 3.2 Characteristic values
293 3.2.1
294 nominal value

295 value of a quantity used to designate and identify a component, device, equipment, or system

296 Note 1 to entry: The nominal value is generally a rounded value.
297 [SOURCE: IEC 60050-151:2001, 151-16-09]
298 3.2.2
299 conventional value

300 measure-value of a standard used in a calibration operation and known with uncertainty

301 negligible with respect to the uncertainty of the instrument to be calibrated

302 Note 1 to entry: This definition is adapted to the object of this standard from the definition of "conventional true

303 value (of a quantity)": value attributed to a particular quantity and accepted, sometimes by convention, as having

304 an uncertainty appropriate for a given purpose.
305 [SOURCE: IEC 60359:2001,3.1.13]
306 3.2.3
307 (measure-) value
308 mid element of the set assigned to represent the measurand

309 Note 1 to entry: The measure-value is no more representative of the measurand than any other element of the

310 set. It is singled out merely for the convenience of expressing the set in the format V ± U, where V is the mid

311 element and U the half-width of the set, rather than by its extremes. The qualifier "measure-" is used when deemed

312 necessary to avoid confusion with the reading-value or the indicated value.

313 Note 2 to entry: For a multiple resistor with switching devices having a zero position, the measure-value for a

314 given setting is the value obtained for that setting minus the residual resistance (see Sub-clause 3.1.12)

315 [SOURCE: IEC 60359:2001,3.1.3, modified – Note 2 to entry has been added.]
316 3.2.4
317 indication
318 reading-value
319 output signal of the instrument

320 Note 1 to entry: The indicated value can be derived from the indication by means of the calibration curve

321 Note 2 to entry: For a material measure, the indication is its nominal or stated value

322 Note 3 to entry: The indication depends on the output format of the instrument:

323 – for analogue outputs it is a number tied to the appropriate unit of the display;

324 – for digital outputs it is the displayed digitized number;
325 – for code outputs it is the identification of the code pattern.

326 Note 4 to entry: For analogue outputs meant to be read by a human observer (as in the index-on-scale

327 instruments) the unit of output in the unit of scale numbering; for analogue outputs meant to be read by another

328 instrument (as in calibrated transducers) the unit of output is the unit of measurement of the quantity supporting

329 the output signal.

330 Note 5 to entry: It is the assigned value for a resistor, the measure-value stated in document (see Sub-clause 9.1

331 p)) for a single or a multiple resistor of classes 0.00005... 0.01, or the nominal value for a single or a multiple

332 resistor of classes 0.01...10.
333 [SOURCE: IEC 60359:2001, 3.1.5, modified – Note 5 to entry has been added.]
334 3.2.5
335 indicated value

336 value given by an indicating instrument on the basis of its calibration curve

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337 Note 1 to entry: The indicated value is the measure-value of the measurand when the instrument is used in a

338 direct measurement under all the operating conditions for which the calibration diagram is valid.

339 [SOURCE: IEC 60359:2001, 3.1.9,]
340 3.2.6
341 stability of measuring instrument
342 stability

343 property of a measuring instrument, whereby its metrological properties remain constant in

344 time

345 EXAMPLE 1 In terms of the duration of a time interval over which a metrological property changes by a stated

346 amount.
347 EXAMPLE 2 In terms of the change of property over a stated time interval.
348 Note 1 to entry: Stability may be quantified in several ways.

349 Note 2 to entry: For resistor, stability is quantified in the change of resistance measure-value over a year. In this

350 document, it is expressed in relative form divided by the resistance measure-value.

351 [SOURCE: ISO/IEC GUIDE 99:2007, 4.19, modified – Note 2 to entry has been added.]

352 3.3 Accuracy class, class index
353 3.3.1
354 accuracy class

355 category of measuring instruments, all of which are intended to comply with a set of

356 specifications regarding uncertainty

357 Note 1 to entry: An accuracy class always specifies a limit of uncertainty (for a given range of influence

358 quantities), whatever other metrological characteristics it specifies.

359 Note 2 to entry: An instrument may be assigned to different accuracy classes for different rated operating

360 conditions.

361 Note 3 to entry: Unless otherwise specified, the limit of uncertainty defining an accuracy class is meant as an

362 interval with coverage factor 2.

363 Note 4 to entry: Accuracy class of a resistor is defined by the limits of intrinsic relative uncertainty, the limits of

364 relative stability and the limits of variations due to influence quantities.
365 [SOURCE: IEC 60359:2001, 3.3.7, modified - Note 4 to entry has been added.]
366 3.3.2
367 class index
368 conventional designation of an accuracy class by a number or symbol
369 [SOURCE: IEC 60050-311:2001, 311-06-10]
370 3.4 Influence quantities, reference conditions, nominal range of use
371 3.4.1
372 influence quantity

373 quantity which is not the subject of the measurement and whose change affects the

374 relationship between the indication and the result of the measurement

375 Note 1 to entry: Influence quantities can originate from the measured system, the measuring equipment or the

376 environment.

377 Note 2 to entry: As the calibration diagram depends on the influence quantities, in order to assign the result of a

378 measurement it is necessary to know whether the relevant influence quantities lie within the specified range.

379 Note 3 to entry: An influence quantity is said to lie within a range C' to C" when the results of its measurement

380 satisfy the relationship: C' ≤ V – U < V + U ≤ C" .
381 [SOURCE: IEC 60359:2001,3.1.14]
382 3.4.2
383 reference conditions

384 appropriate set of specified values and/or ranges of values of influence quantities under which

385 the smallest permissible uncertainties of a measuring instrument are specified

386 Note 1 to entry: The ranges specified for the reference conditions, called reference ranges, are not wider, and

387 are usually narrower, than the ranges specified for the rated operating conditions.

388 [SOURCE: IEC 60359:2001, 3.3.10]
389 3.4.3
390 reference value
391 specified value of one of a set of reference conditions
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