Water quality - Examination and determination of colour (ISO 7887:2011)

ISO 7887:2011 specifies four different methods, designated A to D, for the examination of colour.
The previously most employed method for assessment of water colour in water treatment plants, limnological surveys, etc. was based on the hexachloroplatinate scale. Methods C and D are harmonized with this traditional procedure.
Method A involves examination of apparent colour by visually observing a water sample in a bottle. This gives only preliminary information, for example for use in field work. Only the apparent colour can be reported.
Method B involves determination of the true colour of a water sample using optical apparatus and is applicable to raw and potable water and to industrial water of low colour. A subclause on interferences is included.
Method C involves determination of the true colour of a water sample using optical apparatus for comparison with hexachloroplatinate concentration at wavelength, λ = 410 nm. A subclause on interferences is included.
Method D involves determination of colour by visual comparison with hexachloroplatinate standard solutions and can be applied to raw and drinking water. A subclause on interferences is included.
Methods A and B are appropriate if the colour hue of the sample differs from the hue of the matching solution.
When stating the result, the procedure used (methods A to D) is also recorded.

Wasserbeschaffenheit - Untersuchung und Bestimmung der Färbung (ISO 7887:2011)

Diese Internationale Norm legt vier verschiedene Verfahren, als A bis D benannt, zur Bestimmung der Färbung fest.
Das bisher bei der Beurteilung der Färbung von Wasser in Wasseraufbereitungsanlagen, bei limnologischen Untersuchungen usw. am häufigsten angewendete Verfahren beruht auf der Hexachloroplatinat Skala [1]. Die Verfahren C und D sind mit diesem herkömmlichen Verfahren [2] und [3] abgestimmt.
Verfahren A beinhaltet ein Verfahren zur Untersuchung der scheinbaren Färbung durch Betrachtung einer Wasser¬probe in einer Flasche. Damit wird nur eine vorläufige Information erhalten, beispielsweise bei Untersuchungen vor Ort. Das Ergebnis kann nur als scheinbare Färbung angegeben werden.
Verfahren B beinhaltet ein Verfahren zur Bestimmung der wahren Färbung einer Wasserprobe mit Hilfe eines optischen Gerätes. Es ist auf Roh  und Trinkwasser und auf schwach gefärbtes Industrieabwasser anwendbar. Zu Störungen siehe entsprechender Abschnitt.
Verfahren C beinhaltet ein Verfahren zur Bestimmung der wahren Färbung einer Wasserprobe mit Hilfe eines optischen Gerätes zum Vergleich mit einer Hexachloroplatinat Konzentration bei einer Wellenlänge von λ = 410 nm. Zu Störungen siehe entsprechender Abschnitt.
Verfahren D beinhaltet ein Verfahren zur Bestimmung der Färbung durch visuellen Vergleich mit Hexachloroplatinat Standardlösungen. Es kann auf Roh  und Trinkwasser angewendet werden. Zu Störungen siehe entsprechender Abschnitt.
Die Verfahren C und D werden empfohlen, wenn sich der Farbton der Probe vom Farbton der Vergleichslösung unterscheidet.
ANMERKUNG 1   Unter Umständen ist es erforderlich, stark gefärbte Wässer vor der Untersuchung oder Bestimmung zu verdünnen. Das kann jedoch die physikalisch chemischen Bedingungen verändern und zu einer Farbänderung führen.
ANMERKUNG 2   In dieser Internationalen Norm beschreibt Anhang A eine interne Qualitätskontrolle für alle Verfahren.
Bei der Angabe des Ergebnisses ist das angewendete Verfahren (Verfahren A bis D) unbedingt mit anzu-geben.

Qualité de l'eau - Examen et détermination de la couleur (ISO 7887:2011)

L'ISO 7887:2011 spécifie quatre méthodes différentes, désignées A à D, d'examen de la couleur.
La méthode qui était la plus couramment utilisée pour l'évaluation de la couleur de l'eau dans les installations de traitement de l'eau, les études limnologiques, etc. était basée sur l'échelle de couleur à l'hexachloroplatinate. Les méthodes C et D sont harmonisées avec cette méthode traditionnelle.
La méthode A implique l'examen de la couleur apparente par observation visuelle d'un échantillon d'eau dans une bouteille. Cette méthode donne uniquement une première indication, pour une application sur le terrain, par exemple. Seule la couleur apparente peut être déterminée.
La méthode B implique la détermination de la couleur vraie d'un échantillon d'eau au moyen d'un appareillage optique, et peut être appliquée aux eaux brutes et potables, ainsi qu'aux eaux industrielles faiblement colorées. Un paragraphe concernant les interférences est inclus.
La méthode C implique la détermination de la couleur vraie d'un échantillon d'eau au moyen d'un appareillage optique par comparaison avec la concentration d'hexachloroplatinate à une longueur d'onde λ = 410 nm. Un paragraphe concernant les interférences est inclus.
La méthode D implique la détermination de la couleur par comparaison visuelle avec des solutions étalons d'hexachloroplatinate et peut être appliquée aux eaux brutes et potables. Un paragraphe concernant les interférences est inclus.
Les méthodes A et B sont appropriées si la teinte de l'échantillon diffère de celle de la solution étalon.
Dans le rapport d'essai, le mode opératoire utilisé (méthodes A à D) est également consigné.

Kakovost vode - Pregled in določevanje barve (ISO 7887:2011)

Ta mednarodni standard določa štiri različne metode, označene od A do D, za pregled barve. V preteklosti najpogosteje uporabljana metoda za presojo barve vode v čistilnih napravah, pri limnoloških raziskavah itd. je temeljila na lestvici heksakloroplatinata. Metodi C in D sta usklajeni s tem tradicionalnim postopkom. Metoda A vključuje presojo dejanske barve z vizualnim opazovanjem vodnega vzorca v steklenici. To daje samo predhodne informacije, na primer pri uporabi na terenu. Poročati je mogoče samo o dejanski barvi. Metoda B vključuje določevanje realne barve vodnega vzorca z optično napravo in se uporablja za neobdelano in pitno vodo ter industrijsko vodo, ki ni močno obarvana. Vključena je podtočka o motnjah. Metoda C vključuje določevanje realne barve vodnega vzorca z optično napravo za primerjavo s koncentracijo heksakloroplatinata pri valovni dolžini – 410 nm. Vključena je podtočka o motnjah. Metoda D vključuje določevanje barve z vizualno primerjavo s standardnimi raztopinami heksakloroplatinata in se lahko uporablja za neobdelano in pitno vodo. Vključena je podtočka o motnjah. Metodi A in B sta ustrezni, če se barvni odtenek vzorca razlikuje od odtenka ujemajoče se raztopine. Pri navajanju rezultata se zabeleži tudi uporabljeni postopek (metode od A do D).

General Information

Status
Published
Publication Date
14-Dec-2011
Technical Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
15-Dec-2011
Completion Date
15-Dec-2011

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SLOVENSKI STANDARD
SIST EN ISO 7887:2012
01-junij-2012
1DGRPHãþD
dSIST ISO/DIS 7887:2009
SIST EN ISO 7887:1996
.DNRYRVWYRGH3UHJOHGLQGRORþHYDQMHEDUYH ,62
Water quality - Examination and determination of colour (ISO 7887:2011)
Wasserbeschaffenheit - Untersuchung und Bestimmung der Färbung (ISO 7887:2011)
Qualité de l'eau - Examen et détermination de la couleur (ISO 7887:2011)
Ta slovenski standard je istoveten z: EN ISO 7887:2011
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
SIST EN ISO 7887:2012 en,fr,de

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

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SIST EN ISO 7887:2012
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SIST EN ISO 7887:2012
EUROPEAN STANDARD
EN ISO 7887
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2011
ICS 13.060.60 Supersedes EN ISO 7887:1994
English Version
Water quality - Examination and determination of colour (ISO
7887:2011)

Qualité de l'eau - Examen et détermination de la couleur Wasserbeschaffenheit - Untersuchung und Bestimmung

(ISO 7887:2011) der Färbung (ISO 7887:2011)
This European Standard was approved by CEN on 14 December 2011.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European

Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national

standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same

status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,

Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7887:2011: E

worldwide for CEN national Members.
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SIST EN ISO 7887:2012
EN ISO 7887:2011 (E)
Contents Page

Foreword ..............................................................................................................................................................3

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SIST EN ISO 7887:2012
EN ISO 7887:2011 (E)
Foreword

This document (EN ISO 7887:2011) has been prepared by Technical Committee ISO/TC 147 "Water quality"

in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of which is held by

DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical

text or by endorsement, at the latest by June 2012, and conflicting national standards shall be withdrawn at

the latest by June 2012.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN ISO 7887:1994.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech

Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,

Sweden, Switzerland and the United Kingdom.
Endorsement notice

The text of ISO 7887:2011 has been approved by CEN as a EN ISO 7887:2011 without any modification.

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SIST EN ISO 7887:2012
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SIST EN ISO 7887:2012
INTERNATIONAL ISO
STANDARD 7887
Third edition
2011-12-15
Water quality — Examination and
determination of colour
Qualité de l'eau — Examen et détermination de la couleur
Reference number
ISO 7887:2011(E)
ISO 2011
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SIST EN ISO 7887:2012
ISO 7887:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2011

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or

ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved
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SIST EN ISO 7887:2012
ISO 7887:2011(E)
Contents Page

Foreword ............................................................................................................................................................ iv

1  Scope ...................................................................................................................................................... 1

2  Normative references ............................................................................................................................ 1

3  Terms and definitions ........................................................................................................................... 2

4  Method A: Visual examination ............................................................................................................. 2

5  Method B: Determination of the true colour using optical instruments .......................................... 3

6  Method C: Determination of true colour using optical instruments for determination of

absorbance at wavelength   410 nm ................................................................................................ 5

7  Method D: Visual method for the determination of the colour in natural water ............................. 9

8  Test report ............................................................................................................................................ 10

Annex A (informative) Quality control ............................................................................................................ 12

Annex B (informative) Precision data ............................................................................................................. 13

Bibliography ...................................................................................................................................................... 15

© ISO 2011 – All rights reserved iii
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SIST EN ISO 7887:2012
ISO 7887:2011(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

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

ISO 7887 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical,

chemical and biochemical methods.

This third edition cancels and replaces the second edition (ISO 7887:1994), which has been technically

revised.
iv © ISO 2011 – All rights reserved
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SIST EN ISO 7887:2012
INTERNATIONAL STANDARD ISO 7887:2011(E)
Water quality — Examination and determination of colour

WARNING — Persons using this International Standard should be familiar with normal laboratory

practice. This standard does not purport to address all of the safety problems, if any, associated with

its use. It is the responsibility of the user to establish appropriate safety and health practices and to

ensure compliance with any national regulatory conditions.

IMPORTANT — It is absolutely essential that tests conducted in accordance with this International

Standard be carried out by suitably qualified staff.
1 Scope

This International Standard specifies four different methods, designated A to D, for the examination of colour.

The previously most employed method for assessment of water colour in water treatment plants, limnological

surveys, etc. was based on the hexachloroplatinate scale (Reference [1]). Methods C and D are harmonized

with this traditional procedure (References [2][3]).

Method A involves examination of apparent colour by visually observing a water sample in a bottle. This gives

only preliminary information, for example for use in field work. Only the apparent colour can be reported.

Method B involves determination of the true colour of a water sample using optical apparatus and is applicable

to raw and potable water and to industrial water of low colour. A subclause on interferences is included.

Method C involves determination of the true colour of a water sample using optical apparatus for comparison

with hexachloroplatinate concentration at wavelength,   410 nm. A subclause on interferences is included.

Method D involves determination of colour by visual comparison with hexachloroplatinate standard solutions

and can be applied to raw and drinking water. A subclause on interferences is included.

Methods A and B are appropriate if the colour hue of the sample differs from the hue of the matching solution.

NOTE 1 Under certain circumstances, strongly coloured water samples require dilution before examination or

determination. However, this can alter the physical-chemical conditions leading to a change in colour.

NOTE 2 An internal quality control procedure for all methods specified in this International Standard is given in

Annex A. Precision data are given in Annex B.
When stating the result, the procedure used (methods A to D) is also recorded.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods

ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples

ISO 10523, Water quality — Determination of pH
© ISO 2011 – All rights reserved 1
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SIST EN ISO 7887:2012
ISO 7887:2011(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
apparent colour of water

colour due to dissolved substances and undissolved suspended matter, determined in the original water

sample without filtration or centrifugation
3.2
colour of water

optical property that causes the changing of the spectral composition of transmitted visible light

3.3
dissolved organic carbon
DOC

sum of organically bound carbon present in water originating from compounds passing through a membrane filter of

0,45 µm pore size, including cyanate and thiocyanate
[6]
[ISO 8245:1999, 3.4]

NOTE DOC in natural waters often originates from natgural organic matter (NOM), a complex mixture of compounds

formed as a result of the breakdown of animal and plant material in the environment. The composition of the mixture is

strongly dependent on the environmental source. Spectroscopic methods are often used to characterize the dissolved

organic matter in natural waters (Reference [4]). The ratio of UV absorbance and DOC concentration (specific UV-

absorption, SUVA) has proved to be useful for optimization of water treatment processes.

3.4
specific colour

ratio between the true colour of a sample and its concentration of dissolved organic carbon

3.5
true colour of water

colour due only to dissolved substances, determined after filtration of the water sample through a membrane

filter of pore size 0,45 μm
4 Method A: Visual examination
4.1 Sampling bottles
Colourless bottle, see ISO 5667-3.

Maintain all glassware that comes into contact with the sample in a scrupulously clean condition by washing

with hydrochloric acid [c(HCI)  2 mol l ] or with surfactant cleaning solution which is recommended for

laboratory use. Finally rinse with water for washing (5.4.2) and allow to drain.
4.2 Sampling and samples

Collect samples in bottles (4.1) and carry out the colour test as soon as possible. If storage is unavoidable, the

samples can be stored for up to 5 days in the dark at 4 °C  2 °C. Prevent extensive aeration during storage,

especially in cases where colour-changing redox reactions are likely to occur.
4.3 Procedure
Shake the sample to solubilize any matter that can dissolve.
2 © ISO 2011 – All rights reserved
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SIST EN ISO 7887:2012
ISO 7887:2011(E)

Put the unfiltered sample into a bottle (4.1) and examine the sample in diffused light against a white

background for colour intensity and hue. Allow any suspended matter that settles to do so before examination.

4.4 Qualitative description

State the intensity of the colour (nil, pale, light or dark) and the hue (e.g. yellow, yellowish brown).

EXAMPLE Apparent colour in accordance with ISO 7887, method A: pale, yellowish brown.

5 Method B: Determination of the true colour using optical instruments
5.1 General

The intensity of the colour of a water sample is characterized by its light absorption at the wavelength of

maximum absorption and quantified by measuring the absorption coefficient with a filter photometer or

spectrophotometer. Normally, most of the yellow-brown coloured natural waters, and the coloured waste water

samples of discharges of domestic treatment plants can be measured at 436 nm. Waste water from industrial

waste water treatment plants does not show sufficiently sharp and distinguished absorption maxima. Those

waters shall be examined using the wavelengths specified in 5.2.
5.2 Principle

Characterization of the intensity of colour of a water sample is performed by measuring the attenuation

(absorption) of light. Different colours cause maximum absorption at different wavelengths of the incident

radiation. In accordance with Method B of this International Standard, the colour of the water is determined

using a photometer or a spectrometer at a minimum of three different wavelengths, distributed over the range

of the visible spectrum:
a) (1)  436 nm;
b) (2)  525 nm;
c) (3)  620 nm.

Always use the wavelength   436 nm (Hg 436 nm); wavelengths (2) and (3) can differ slightly from those

specified above, depending on the type of optical filter employed. For a better characterization, measurements

at additional wavelengths near the absorption maximum can be performed.
5.3 Interferences

Prior to measurement, the water sample is filtered (5.7) to avoid interferences by undissolved matter. This

filtration can, however, lead to further interferences (e.g. due to oxidation reactions caused by contact with air

or due to precipitations initiated by the filtration step). As an example, iron and manganese compounds can be

retained on the filter or transferred to a coloured oxidation state. In some cases, particularly in the presence of

colloidal solids, e.g. clay or other finely dispersed matter, it can prove impossible to obtain a clear filtrate. In

this case, mention in the test report that colloidal solids are present.

NOTE Colours often depend on pH. Therefore, the pH of the water sample is regularly determined in parallel with

optical measurements and these results are reported with the other findings.
© ISO 2011 – All rights reserved 3
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SIST EN ISO 7887:2012
ISO 7887:2011(E)
5.4 Reagents
5.4.1 Optically pure water

Soak a membrane filter, of pore size 0,2 μm, in distilled or deionized water for approximately 1 h. Pass

approximately 1 l of water, grade 1, as specified in ISO 3696 through the prepared filter, discarding the first

50 ml of filtrate.

NOTE If freshly distilled or deionized water has no measurable absorbance, it can be used.

5.4.2 Water for washing
Water, grade 3, as specified in ISO 3696.
5.5 Apparatus

5.5.1 Spectrophotometer (option 1), for continuous or discontinuous measurement, suitable for the visible

range of the spectrum (approximately from 330 nm to 780 nm), preferably a scanning double beam instrument

with bandwidth 10 nm.

5.5.2 Filter photometer (option 2), for discontinuous measurements, equipped with spectral line filters

having a bandwidth which is as small as possible (about 20 nm), allowing measurements to include

wavelengths 436 nm, 525 nm and 620 nm.
5.5.3 Membrane filter assembly, with filters of pore size 0,2 μm and 0,45 μm.
5.5.4 pH-meter.
5.6 Sampling and samples
See 4.2.
5.7 Procedure

Set up either the spectrophotometer (5.5.1) or filter photometer (5.5.2) and strictly observe the operating

manual supplied by the manufacturer of the instrument. Prior to examination, filter the water sample through a

membrane filter of pore size 0,45 μm (5.5.3). In parallel with each colour determination, measure the pH of the

filtered sample in accordance with ISO 10523. In the case of strong colours, it can be necessary to use optical

cells with suitable pathlengths down to 1 mm. The water sample can also be diluted with a measured volume

of optically pure water (5.4.1), as appropriate, after filtration. The pH shall be measured before and after

dilution.

Transfer the sample to the optical cell of the spectrophotometer or filter photometer and place optically pure

water (5.4.1) in the reference cell.

If the spectral absorption coefficient, , at the wavelength, , is less than 0,1 cm , the optical pathlength of

the cell should be 10 mm or more.

NOTE 1 A cell of optical pathlength down to 1 mm can be used to avoid diluting the sample.

Measure natural waters at 436 nm against optically pure water (5.4.1). Perform further measurements at

525 nm and 620 nm.

NOTE 2 In order to determine the absorption maximum, the entire absorption spectrum between 350 nm and 780 nm

can be taken, using a scanning spectrophotometer (5.5.1).
4 © ISO 2011 – All rights reserved
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SIST EN ISO 7887:2012
ISO 7887:2011(E)
5.8 Calculation

Calculate the spectral absorption coefficient,  (), absorbance per metre, using Equation (1):

  f (1)
where
A is the absorbance of the water sample at wavelength ;
d is the optical pathlength, in millimetres, of the cell;

f is a factor to give the spectral absorption coefficient, in reciprocal metres (f  1 000).

The volume of water used for dilution should be taken into account when stating the result.

NOTE Most
...

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