Hydrometry - Selection, establishment and operation of a gauging station (ISO 18365:2013)

ISO 18365:2013 gives requirements for the establishment and operation of a gauging station for the measurement of stage, or stage and discharge, of a lake, reservoir, river or canal or other artificial open channel. It also describes how a gauging station utilising one of the measurement methods listed should be operated and maintained.
Requirements are provided for stage only measurement stations, stage-discharge stations and direct-discharge measurement stations in natural channels, as well as for stage-discharge stations with artificial structures. Additionally, some requirements are given for measurements under difficult conditions, such as under ice conditions.

Hydrometrie - Auswahl, Einrichtung und Betrieb einer Pegelstation (ISO 18365:2013)

Diese Internationale Norm enthält Anforderungen zur Einrichtung und zum Betrieb einer Pegelstation zum Messen des Wasserstands oder des Wasserstands und Durchflusses eines Sees, Stausees, Flusses, Kanals oder eines anderen künstlichen offenen Gerinnes. Sie beschreibt auch, wie eine Pegelstation, an der eine der aufgeführten Messverfahren angewendet wird, betrieben und unterhalten werden sollte.
Es werden Anforderungen für reine Wasserstands-Pegel, für Pegel mit Wasserstand-Durchfluss-Beziehung und für Pegel mit direkter Durchflussmessung in natürlichen Gerinnen sowie für Wasserstand-Durchfluss-Pegel mit Messbauwerken bereitgestellt. Zusätzlich werden einige Anforderungen zu Messungen unter schwierigen Bedingungen gegeben, wie zum Beispiel bei Eis.

Hydrométrie - Sélection, établissement et exploitation d'une station hydrométrique (ISO 18365:2013)

L'ISO 18365:2013 donne des exigences pour l'établissement et l'exploitation d'une station hydrométrique destinée à la mesure de la hauteur, ou de la hauteur et du débit, d'un lac, d'un réservoir, d'une rivière, d'un canal ou autre canal découvert artificiel. Elle décrit aussi la manière dont il convient d'exploiter et de maintenir une station hydrométrique utilisant une des méthodes de mesure citées.
Des exigences sont fournies pour les stations de mesurage de la hauteur seulement, les stations de mesurage hauteur-débit et les stations de mesurage direct du débit dans des canaux naturels, et aussi pour les stations de mesurage hauteur-débit avec des ouvrages artificiels. Des exigences sont données, en plus, pour les mesurages effectués dans des conditions difficiles, sous la glace par exemple.

Hidrometrija - Izbira, postavitev in delovanje merilne postaje (ISO 18365:2013)

General Information

Status
Published
Publication Date
03-Dec-2013
Technical Committee
Drafting Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
13-Aug-2013

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SLOVENSKI STANDARD
SIST EN ISO 18365:2014
01-februar-2014
Hidrometrija - Izbira, postavitev in delovanje merilne postaje (ISO 18365:2013)
Hydrometry - Selection, establishment and operation of a gauging station (ISO
18365:2013)

Hydrometrie - Auswahl, Einrichtung und Betrieb einer Pegelstation (ISO 18365:2013)

Hydrométrie - Mesurage du débit des liquides dans les canaux découverts (ISO
18365:2013)
Ta slovenski standard je istoveten z: EN ISO 18365:2013
ICS:
17.120.20 Pretok v odprtih kanalih Flow in open channels
SIST EN ISO 18365:2014 en

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

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SIST EN ISO 18365:2014
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SIST EN ISO 18365:2014
EUROPEAN STANDARD
EN ISO 18365
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2013
ICS 17.120.20
English Version
Hydrometry - Selection, establishment and operation of a
gauging station (ISO 18365:2013)

Hydrométrie - Sélection, établissement et exploitation d'une Hydrometrie - Auswahl, Einrichtung und Betrieb einer

station hydrométrique (ISO 18365:2013) Pegelstation (ISO 18365:2013)
This European Standard was approved by CEN on 19 November 2013.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United

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

© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18365:2013 E

worldwide for CEN national Members.
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SIST EN ISO 18365:2014
EN ISO 18365:2013 (E)
Contents Page

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

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SIST EN ISO 18365:2014
EN ISO 18365:2013 (E)
Foreword

This document (EN ISO 18365:2013) has been prepared by Technical Committee ISO/TC 113 “Hydrometry”

in collaboration with Technical Committee CEN/TC 318 “Hydrometry” the secretariat of which is held by BSI.

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 2014, and conflicting national standards shall be withdrawn at

the latest by June 2014.

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.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 18365:2013 has been approved by CEN as EN ISO 18365:2013 without any modification.

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SIST EN ISO 18365:2014
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SIST EN ISO 18365:2014
INTERNATIONAL ISO
STANDARD 18365
First edition
2013-12-15
Hydrometry — Selection,
establishment and operation of a
gauging station
Hydrométrie — Sélection, établissement et exploitation d’une station
hydrométrique
Reference number
ISO 18365:2013(E)
ISO 2013
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SIST EN ISO 18365:2014
ISO 18365:2013(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2013

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

or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior

written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of

the requester.
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Tel. + 41 22 749 01 11
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E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved
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SIST EN ISO 18365:2014
ISO 18365:2013(E)
Contents Page

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

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

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

3 Terms, definitions and symbols ............................................................................................................................................................ 1

4 General requirements and considerations ............................................................................................................................... 1

4.1 Requirements ........................................................................................................................................................................................... 1

4.2 Other constraints .................................................................................................................................................................................. 2

5 Water level (Stage) only gauging stations .................................................................................................................................. 2

5.1 Preliminary survey and selection criteria ....................................................................................................................... 2

5.2 Stage measurement and recording ........................................................................................................................................ 3

6 Stage-discharge gauging stations ........................................................................................................................................................ 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Main elements of a stage-discharge gauging station ............................................................................................. 5

7 Stage- discharge gauging stations using hydraulic structures.............................................................................. 6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Site selection ............................................................................................................................................................................................. 6

7.3 Types of hydraulic structures ..................................................................................................................................................... 6

8 Velocity-discharge gauging stations ................................................................................................................................................. 7

8.1 Applications and types of instrument ................................................................................................................................. 7

8.2 Site selection ............................................................................................................................................................................................. 8

8.3 Calibration .................................................................................................................................................................................................. 8

8.4 Transit time (acoustic) method ................................................................................................................................................ 8

8.5 Doppler .......................................................................................................................................................................................................... 9

8.6 Acoustic (echo) correlation velocity meters ..............................................................................................................10

8.7 Electromagnetic method (Full channel width coil) ..............................................................................................10

9 Measurement under difficult conditions .................................................................................................................................10

9.1 Ice and frost conditions ................................................................................................................................................................10

9.2 Weed growth ..........................................................................................................................................................................................11

9.3 Extreme sedimentation conditions ....................................................................................................................................11

10 Operation and maintenance ..................................................................................................................................................................11

10.1 General ........................................................................................................................................................................................................11

10.2 Water level (Stage) only gauging stations ....................................................................................................................11

10.3 Stage-discharge gauging stations.........................................................................................................................................12

10.4 Stage-discharge gauging stations using hydraulic structures .....................................................................12

10.5 Velocity-discharge gauging stations ..................................................................................................................................12

Annex A (informative) Applicable conditions for selection of discharge measurement method ......13

Bibliography .............................................................................................................................................................................................................................16

© ISO 2013 – All rights reserved iii
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SIST EN ISO 18365:2014
ISO 18365:2013(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives

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. Details of any

patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received. www.iso.org/patents

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers

to Trade (TBT) see the following URL: Foreword - Supplementary information

The committee responsible for this document is ISO/TC 113, Hydrometry, Subcommittee SC 1, Velocity

area methods.

ISO 18365 cancels and replaces ISO 1100-1:1996 and ISO/TR 8363:1997, which have been merged and

technically revised.
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SIST EN ISO 18365:2014
INTERNATIONAL STANDARD ISO 18365:2013(E)
Hydrometry — Selection, establishment and operation of a
gauging station
1 Scope

This International Standard gives requirements for the establishment and operation of a gauging station

for the measurement of stage, or stage and discharge, of a lake, reservoir, river or canal or other artificial

open channel. It also describes how a gauging station utilizing one of the measurement methods listed

should be operated and maintained.

Requirements are provided for stage only measurement stations, stage–discharge stations and direct-

discharge measurement stations in natural channels, as well as for stage–discharge stations with

artificial structures. Additionally, some requirements are given for measurements under difficult

conditions, such as under ice conditions.
2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

ISO 772, Hydrometry — Vocabulary and symbols
3 Terms, definitions and symbols

For the purposes of this document, the terms, definitions and symbols given in ISO 772 apply.

4 General requirements and considerations
4.1 Requirements

Before commencing work on establishment and operation of a gauging station, the following requirements

shall be identified:
a) range of levels required to be measured;
b) range of flows required to be measured;
c) customer’s requirements for type of data;
d) customer’s requirements for timeliness of data;
e) allowable uncertainty in the results;
f) other potential users of the data;
g) life expectancy of the station;
h) available budget;
i) agreements for access to land and construction permits.
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SIST EN ISO 18365:2014
ISO 18365:2013(E)
4.2 Other constraints

In addition to the requirements as in 4.1, other constraints shall be identified including the following:

a) local environmental issues;
b) accessibility of the site under all conditions of flow;
c) availability of power and communication links;
d) stability of the watercourse embankments;
e) stability of the watercourse bed;

f) identification of any proposed hydraulic modifications planned for the future;

e.g. bridges, tunnels (including pipe crossings), harbours or piers;
g) potential of vandalism;
h) influence of submergence of the gauging site due to downstream impounding
structures (lakes, dams, weirs);
i) potential stream losses in karst areas;
j) aquatic weed growth in the watercourse;
k) ice conditions during winter in cold and arctic regions.

Knowledge of the above requirements and local constraints will ensure the provision of appropriate

measurement and recording facilities as well as the adoption of an appropriate maintenance philosophy.

5 Water level (Stage) only gauging stations
5.1 Preliminary survey and selection criteria
5.1.1 General

The site selected for determination of stage shall be selected according to the purpose for which the

readings are required. Accessibility of the site and the availability of an observer if the gauge is to be

non-recording are important criteria as is the availability of an appropriate power supply and data

communication capabilities if the gauge is to be recording.

Gauges on lakes and reservoirs are normally located near the outlet, but shall be located sufficiently far

away from the zone where an increase in velocity causes a drawdown in water level. Gauges on large

bodies of water shall also be located so as to reduce the effect of strong winds which may cause misleading

data which may not be representative of the body of water being measured. Hydraulic conditions

(preferably a sufficiently long uniform stretch of water channel with uniform bed topography) are

important factors in site selection in open channels, particularly where water levels may later be used

in the computation of discharge. To ensure repeatability of the readings, ideally a bed or channel control

shall be present, which itself shall be stable and sensitive to changes in the level of the water. For the

purpose of monitoring water levels e.g. for flood warning purposes, this may not be a strict requirement.

5.1.2 Preliminary survey

A detailed examination of a 1:50,000 or larger scale map of the area is required in the first instance.

Aerial surveys, satellite imagery, or maps available in the public domain such as Google Earth can be

used as a basis for selecting potential sites, which can then be evaluated more precisely by ground

reconnaissance. This will include a detailed visual examination. Enquiries shall be made to determine

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SIST EN ISO 18365:2014
ISO 18365:2013(E)

whether or not any plans exist for the modification of the river reach which would modify the stream

bed regime and would have an impact on the proposed gauging station.

Enquiries shall also be made into any known past flow history including low water events, floods and

other high water events, existence of any overflow area leading to flow by-passing the site, and very

importantly, any knowledge of bed instability.

It may be appropriate to discuss and outline proposals at an early stage with the owners of the site

identified to ensure they are amenable to the proposed installation.

Surveys of channel geometry and flow velocity patterns using an Acoustic Doppler Current Profiler may

provide useful information.

Collection of data from hydrometric measurement stations is dominated by the use of telemetry;

availability and quality of methods of data transmission shall be investigated.
5.1.3 Selection criteria

A list of potential sites shall be established with their advantages and disadvantages identified. Site

selection can then be made according to the criteria identified in Clause 4. The establishment of the

gauge zero shall be chosen so as to avoid negative readings. Thus it shall be set well below the level of the

control feature. This zero point shall be correlated with a national datum through a station benchmark

and should be checked annually with respect to this benchmark. This will ensure that, should loss or

damage to the reference gauge occur, it can be replaced at exactly the same level.

The benchmark itself shall be checked regularly in order to confirm that it still represents the national

datum. The frequency of such checks shall be dependent on local soil dynamics.
5.2 Stage measurement and recording
5.2.1 General

The reading of stage may be required as a single instantaneous measurement, as a short series of

instantaneous measurements or as a continuous or practically continuous record of the fluctuations of

stage. The basis of any of the above shall include the installation of a vertical staff gauge, a ramp gauge,

or a wire-weight gauge.
5.2.2 Vertical staff gauge

A vertical staff gauge comprises a scale (normally 1 metre in length with graduations or scale divisions

of 5 or 10 mm) marked on or securely attached to a suitable and stable vertical surface. The gauge shall

be made of material with a low coefficient of expansion. Where the range of measurement required

exceeds the capacity of a single vertical gauge, other gauges shall be installed on the line of a cross-

section normal to the direction of flow. The scales on such a series of stepped staff gauges shall overlap

by not less than 15 cm in order to safeguard continuity of readings and also to confirm their consistency

with each other.
5.2.3 Ramp or inclined gauge

A ramp or inclined gauge consists of a scale marked on or securely attached to a suitable and stable

inclined surface, which conforms closely to the contour of the river bank. The gauge shall be made of

material with a low coefficient of expansion. Throughout its length the gauge may lie on one continuous

slope or may be a compound of two or more slopes. The gauge shall lie on a line of a cross-section normal

to the direction of flow.
5.2.4 Wire or tape weight gauge

A wire or tape weight gauge consists of a weight which is manually lowered until the weight touches

the surface of the water. The wire or tape may be wound on a drum attached to a winding mechanism

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ISO 18365:2013(E)

or it may be a hand reel. The wire or tape gauge can be equipped with electrical contacts to improve

measurements, when there is a large vertical distance between the measuring point and the water

surface.
5.2.5 Other methods

It may be appropriate in some cases to use alternative methods for single or continuous determinations

of water level. Such methods, including maximum level gauges, are described in ISO 4373.

5.2.6 Stage recording

Customer requirements shall dictate the method of recording stage. It may be that a single record of

stage taken daily and read manually will suffice in which case a suitable person to do this work should

be identified.

It is more common to provide a continuous record of stage utilizing water level sensors, such as floats,

pressure transducers, and echo sounders, interfaced with a digital recorder (logger or telemetry) or

analog recorder (chart). Details of such systems, including the use of stilling wells, can be found in

ISO 4373. Modern gauging stations typically have two independent systems for stage measurement to

avoid or reduce data losses.

When a recorder is used, visits by the observer should be made from time to time to ensure satisfactory

performance of the sensor and recorder. It is recommended that the observer notes the time and date

of such checks along with the staff gauge and recorder values. It is essential that the staff gauge itself is

maintained in such a way as to be safely accessible and directly legible to the observer.

Comments on the state of the channel, river banks, presence of any obstruction, prevailing flow

conditions, etc. shall also be noted.

The frequency of such visits shall be subject to country-specific requirements but it is important that a

site visit shall follow a major hydraulic event to confirm continued measurement and recording of data.

6 Stage-discharge gauging stations
6.1 General

When records of water level are to be used as a basis for computation of discharge, the relation between

water level and flow must be determined.

In a stable channel with an appropriate control feature which is stable and sensitive, a single relation

may exist between water level and discharge. In this case, the relation can be determined by taking

discharge measurements throughout the range of levels and flows required to be measured.

Several techniques are available for this purpose including, but not limited to, current meter gauging

and float gauging (see ISO 748), dilution gauging (see ISO 9555-1, ISO 9555-3 and ISO 9555-4), transit

time acoustic methods (see ISO 6416), Doppler velocity meters (see ISO 15769), electromagnetic current

meters (see ISO/TS 15768) or acoustic Doppler current meters (see ISO/TR 24578).

The frequency of any maintenance or operational performance shall be such that the accuracy and

timeliness of data provision meets the user’s requirements.
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ISO 18365:2013(E)
6.2 Main elements of a stage-discharge gauging station
6.2.1 General

The main elements required for the purpose of determining discharge in a stream from water level

records are as follows:
a) a stage measuring device (see 5.2.1);
b) a stage sensing and recording device (see 5.2.6);
c) a control section or reach (see 6.2.2);
d) a section suitable for discharge measurements (see 6.1 and 6.2.3);
e) discharge measurements for defining a stage-discharge relation (see 6.2.4).
6.2.2 Control section or control reach

A control section or control reach of a channel is a natural or artificial section or reach whose physical

characteristics can be measured and used to determine the relationship between stage and discharge.

In a control section any change in the stage downstream of the control does not affect the stage upstream

of the control. Whatever the discharge in the control section, a critical stage can be determined.

It shall be stable, i.e. no change shall occur over time to its physical characteristics. Regular inspection

of the control section shall be carried out to ensure that no changes have taken place which would alter

the relationship between stage and discharge at this site.

More than one control section may be required for discharge measurement at one gauging station

particularly when the range of levels and flows is substantial. For example, under certain flow conditions

a downstream control reach may create a water level which submerges an upstream weir which had

been acting as a control.

The sensitivity of a control section or reach shall be such that any significant change in discharge shall

result in either a measurable change in stage (for control sections) or a measurable change in stage at

one extremity of the control reach.
6.2.3 Section suitable for discharge measurements

Regardless of the method of measurement, the discharge through the discharge measuring section shall

be the same as the discharge normal to the reference staff gauge, over the range of flows to be measured.

Different measuring sections or different methods of measurement may be used to cover the range of

flows required.

A full description of a site suitable for measurement of discharge using current meters or floats is

given in ISO 748. Site requirements for dilution gauging are given in ISO 9555 Parts 1, 3, and 4. Site

requirements for the application of acoustic transit time velocity measurement techniques are given in

ISO 6416. Site requirements for the application of acoustic velocity meters using the Doppler and echo

correlation techniques are given in ISO 15769. Site requirements for the application of electromagnetic

techniques are given in ISO 9213.
6.2.4 Discharge measurements

Discharge measurements using the above techniques shall be related to a stage reading taken at the

beginning and end of the discharge measurement and during the measurement if the stage is changing

rapidly or inconsistently. When sufficient numbers of discharge measurements have been taken, a

stage–discharge relationship can be computed (see ISO 1100-2). Subsequent to the formulation of this

stage-discharge relationship, only occasional discharge measurements need be taken at flows in the

normal range to confirm the robustness of the relationship unless the site is subject to shifting control

© ISO 2013 – All rights reserved 5
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