ISO 7078:2020

Buildings and civil engineering works - Procedures for setting out, measurement and surveying - Vocabulary

This document defines terms that are commonly used in procedures for setting out, measurement and surveying in buildings and civil engineering works.

Construction immobilière — Procédés pour l'implantation, le mesurage et la topométrie — Vocabulaire

General Information

• Status: Published
• Publication Date: 16-Apr-2020
• ICS: 01.040.91 - Construction materials and building (Vocabularies)
• ICS: 91.200 - Construction technology
• Technical Committee: ISO/TC 59/SC 2 - Terminology and harmonization of languages
• Drafting Committee: ISO/TC 59/SC 2/WG 4 - Maintenance of terminology standards and policies
• Current Stage: 9060 - Close of review
• Completion Date: 02-Dec-2030

Relations

• Revises: ISO 7078:1985 - Building construction - Procedures for setting out, measurement and surveying - Vocabulary and guidance notes
• Effective Date: 31-Mar-2018

Overview

ISO 7078:2020 - Buildings and civil engineering works - Procedures for setting out, measurement and surveying - Vocabulary - is an international vocabulary standard that defines terms commonly used in setting out, measurement and surveying for construction and civil engineering. Published as the second edition in 2020, the document replaces ISO 7078:1985 and provides a harmonized language to improve communication among surveyors, engineers, contractors and other construction professionals.

Key topics

The standard organizes terminology into focused sections and provides internationally preferred terms (with country‑specific synonyms where applicable). Key technical topics include:

• General measurement concepts: measurement, measurand, measuring instrument, measurement result, measurement error, metrology.
• Setting out and surveying: setting out (laying out), coordinate systems, geodetic vs. local systems, level, height.
• Positioning and GNSS: GNSS, GPS, differential GNSS, real‑time kinematic positioning (RTK) - note: RTK is described as enabling positioning with precision better than 10 cm.
• Measuring equipment and parts: measuring tools, measuring instruments, measuring systems, ancillary and auxiliary equipment, gauges.
• Quality and calibration: measurement standard, calibration, testing of measuring instruments, measurement uncertainty (conceptual coverage).
• Scales and methods: entries on scales, reading, observation and measurement methods used in building and civil engineering surveying.

The publication contains a foreword, introduction, bibliography and index; there are no normative references. It was prepared by ISO/TC 59/SC 2 (Terminology and harmonization of languages).

Practical applications

ISO 7078:2020 is primarily a vocabulary reference to ensure consistent use of terms across international construction projects and multidisciplinary teams. Typical uses:

• Producing clear technical specifications, contracts and tender documents that involve surveying and setting out.
• Aligning terminology in quality assurance, site measurement procedures and calibration records.
• Supporting interoperability between surveying teams, equipment vendors and software by providing agreed definitions for concepts like GNSS, coordinate systems and measurement uncertainty.
• Training, education and documentation for surveyors, site engineers, architects and measuring technicians.
• Harmonizing language in cross‑border projects and international procurement.

Related standards

ISO 7078 references and aligns with other ISO terminologies and guides, for example:

• ISO 6707‑1 / ISO 6707‑2 (building terms)
• ISO Guide 99 (VIM - vocabulary of metrology)
• ISO 14978 (measuring equipment concepts)
• ISO 15638 and ISO 19130 (GNSS and positioning terminology)
• ISO 9849 (GNSS processing applications)

Keywords: ISO 7078:2020, setting out, surveying vocabulary, measurement, GNSS, calibration, construction surveying, measurement uncertainty, metrology.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7078
Second edition
2020-04
Buildings and civil engineering
works — Procedures for setting
out, measurement and surveying —
Vocabulary
Construction immobilière — Procédés pour l'implantation, le
mesurage et la topométrie — Vocabulaire
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Quality of measurement . 6
3.3 Scales .10
3.4 Measuring tools .12
3.5 Measuring instruments and their parts .15
3.6 Methods of measuring .19
Bibliography .29
INDEX .30
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 (see 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 (see 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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 59, Buildings and civil engineering works,
Subcommittee SC 2, Terminology and harmonization of languages.
This second edition cancels and replaces the first edition (ISO 7078:1985), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— removal of diagrams describing traditional practices and statistical methods;
— renumbering of all entries;
— terms previously discussed in groups now separated and presented as individual entries.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

Introduction
This document has been revised to be compatible with the series of vocabularies being produced by
TC 59/SC 2 spanning across several domains within the construction sector. With the growth in the
number of international construction projects and the development of the international market for
construction products, there is an increasing need for an agreement on a common language across
disciplines.
The practical realization of dimensional accuracy in relation to buildings and civil engineering
works involves not only land surveyors and measuring technicians but also professionals engaged
in the different stages of the construction process. Further, the widespread use of optical measuring
instruments and associated electro-optical techniques, many of which make provision for automatic
communication of information, makes smooth communication between different professions
necessary. In order to promote such a communication agreement on terms and concepts used in setting
out, measurement and surveying is necessary. The purpose of this document is, therefore, to provide
a consistent language for use by the various professions involved in measurement in the construction
industry.
International preferred terms are listed in boldface type. Where a preferred term is specific to a
particular English-speaking country, e.g. the United States of America, etc., it is given below the
international preferred term and is annotated with the relevant country code. Where no preferred
terms are listed indicating usage in a specific geographical location, this signifies that the international
preferred term is the accepted term in the English-speaking countries. A term beneath the preferred
term not given in boldface type is an admitted (non-preferred) synonym. A country code is assigned to
an admitted term if it is specific to a particular English-speaking country.
INTERNATIONAL STANDARD ISO 7078:2020(E)
Buildings and civil engineering works — Procedures for
setting out, measurement and surveying — Vocabulary
1 Scope
This document defines terms that are commonly used in procedures for setting out, measurement and
surveying in buildings and civil engineering works.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
NOTE ISO 6707-1 defines general terms for buildings and civil engineering works.
3.1 General terms
3.1.1
measurement
operation that has the object of determining the value of a quantity
[SOURCE: ISO 6707-1:2017, 3.5.1.22, modified — Note 1 to entry has been omitted.]
3.1.2
setting out
layout, US
laying out, US
establishment of marks and lines to define the position and level of the elements for the construction
work so that work can proceed with reference to them
[SOURCE: ISO 6707-2:2017, 3.3.13]
3.1.3
metrology
science of measurement (3.1.1) and its application
Note 1 to entry: Metrology includes all theoretical and practical aspects of measurement, whatever the
measurement uncertainty and field of application.
[SOURCE: ISO Guide 99:2007, 2.2]
3.1.4
geodesy
science of measurement (3.1.1) on or in the vicinity of the ground to determine form, dimensions and
the distribution of mass and fields of gravity on the earth or parts of it
Note 1 to entry: Surveying is the science of measurements necessary to determine the locations of points
(features) on or beneath the surface of the earth.
Note 2 to entry: Where measurements cover such a large part of the earth’s surface that the curvature cannot be
ignored, then the operations are termed geodetic surveying or measuring.
3.1.5
photogrammetry
technique of measurement (3.1.1) using photographs, for example aerial photographs, to determine,
primarily, geometric properties such as size, location and form of objects
Note 1 to entry: Photogrammetric measurement is often used for mapping, but also has some engineering
applications.
3.1.6
measurand
quantity intended to be measured
Note 1 to entry: The measurand including the measuring system (3.1.19) and the conditions under which the
measurement (3.1.1) is carried out, might change the phenomenon, body, or substance such that the quantity
being measured may differ from the measurand as defined. In this case, adequate correction (3.2.15) is necessary.
[SOURCE: ISO/IEC Guide 99:2007, 2.3, modified — EXAMPLEs and NOTEs 2 to 4 have been omitted.]
3.1.7
measuring instrument
device used for making measurements (3.1.1) or for levelling (3.6.4)
Note 1 to entry: Measuring instruments are sometimes used in conjunction with one or more supplementary
devices.
3.1.8
measuring equipment
measuring instrument (3.1.7), material measure, software, measurement standard (3.1.14), reference
material, ancillary equipment (3.1.9) or auxiliary equipment (3.1.10) used in a measurement (3.1.1)
Note 1 to entry: The definition is necessarily wider than that of measuring instrument since it includes all the
devices used in a measurement.
[SOURCE: ISO 14978:2018, 3.5.1, modified — In the definition, “indicating” has been omitted from
beginning, and “ancillary equipment” has been inserted before “auxiliary equipment”; Note 2 to entry
has been omitted.]
3.1.9
ancillary equipment
equipment additional to the actual measuring instrument (3.1.7) used when carrying out
measurements (3.1.1)
EXAMPLE Pegs, sighting targets (3.6.67) and chalk marking lines.
3.1.10
auxiliary equipment
equipment that gives aid or support to a measuring instrument (3.1.7)
EXAMPLE Tripod.
3.1.11
measuring tool
simple measuring device
EXAMPLE Folding rule (3.4.5), measuring tape (3.4.1), square (3.4.12).
2 © ISO 2020 – All rights reserved

3.1.12
indication
quantity value provided by a measuring instrument (3.1.7) or a measuring system (3.1.19)
Note 1 to entry: An indication may be presented in visual or acoustic form or may be transferred to another
device. An indication is often given by the position of a pointer on the display for analogue outputs, a displayed
or printed number for digital outputs, a code pattern for code outputs, or an assigned quantity value for material
measures.
Note 2 to entry: An indication and a corresponding value of the quantity being measured are not necessarily
values of quantities of the same kind.
[SOURCE: ISO/IEC Guide 99:2007, 4.1]
3.1.13
measurement result
set of quantity values being attributed to a measurand (3.1.6) together with other available relevant
information
Note 1 to entry: A measurement result generally contains “relevant information” about the set of quantity values,
such that some may be more representative of the measurand than others. This may be expressed in the form of
a probability density function (PDF).
Note 2 to entry: A measurement result is generally expressed as a single measured quantity value and a
measurement of uncertainty. If the measurement uncertainty is considered negligible for some purpose, the
measurement result may be expressed as a single measured quantity value. In many fields, this is the common
way of expressing a measurement result.
[SOURCE: ISO/IEC Guide 99:2007, 2.9, modified — NOTE 3 has been omitted.]
3.1.14
measurement standard
realization of the definition of a given quantity value and associated measurement (3.1.1) uncertainty,
used as a reference
[SOURCE: ISO Guide 99:2007, 5.1, modified — EXAMPLEs and NOTEs have been omitted.]
3.1.15
observation
act of measuring or otherwise determining the value of a property
[SOURCE: ISO 19109:2015, 4.16]
3.1.16
reading
part of an observation (3.1.15) which only involves the operator’s notations of values on a scale (3.3.1) or
other methods of recording values
3.1.17
measurement error
measured quantity value minus a reference quantity value
Note 1 to entry: Measurement error should not be confused with production error or mistake.
Note 2 to entry: A “reference quantity value” is a quantity value used as a basis for comparison.
[SOURCE: ISO/IEC Guide 99:2007, 2.16, modified — NOTE 1 has been omitted; NOTE 2 has been
renumbered as Note 1 to entry; new Note 2 to entry has been added.]
3.1.18
gauge
bar of steel or other suitable material of standard length, accurately made, for the purpose of checking
or verification of length measuring devices
3.1.19
measuring system
set of one or more measuring instruments (3.1.7) and often other devices, including any reagent and
supply, assembled and adapted to give information used to generate measured quantity values within
specified intervals for quantities of specified kinds
Note 1 to entry: A measuring system may consist of only one measuring instrument.
[SOURCE: ISO/IEC Guide 99:2007, 3.2]
3.1.20
coordinate system
two-dimensional or three-dimensional reference system for defining the location points on a surface or
in space by means of distances (rectangular/Cartesian co-ordinates) or angles (angles co-ordinates) or
both (polar co-ordinates), with relation to designated angles or planes
Note 1 to entry: In land surveying, the x-axis may be in the direction of astronomic (true) north, magnetic north,
for example grid north, with the y-axis towards east. The z-axis points approximately upwards (towards the
zenith). In some countries, the x- and y- axes are reversed whilst in others E, N and H are used to refer to “East”,
“North” and “Height”.
Note 2 to entry: In building surveying, a local orthogonal system is often set up with the reference axes parallel
to the building axes or chosen at the convenience of the surveyor.
3.1.21
geodetic coordinate system
coordinate system (3.1.20) in which position is specified by geodetic latitude, geodetic longitude and (in
the three-dimensional case) ellipsoidal height (3.1.24)
[SOURCE: ISO 19130-1:2018, 3.22]
3.1.22
geographic coordinates
angular coordinates (angular distances) expressed as latitude and longitude to define a point on the
surface of the earth with reference to the equator and the meridian of Greenwich
3.1.23
level
value of the vertical dimension of a point above or below a defined reference
[SOURCE: ISO 6707-1:2017, 3.7.2.39]
3.1.24
height
vertical dimension above a horizontal reference level (3.1.23)
EXAMPLE Distance of a feature above the ground – height of a building.
[SOURCE: ISO 6707-1:2017, 3.7.2.36, modified — EXAMPLE has been added.]
3.1.25
global positioning system
GPS
instantiation of GNSS (3.1.26) controlled by the US Department of Defence
[SOURCE: ISO 15638-12:2014, 4.25]
4 © ISO 2020 – All rights reserved

3.1.26
global navigation satellite system
GNSS
system that comprises several networks of satellites that transmit radio signals containing time and
distance data that can be picked up by a receiver, allowing the user to identify the location of the
receiver anywhere around the world
[SOURCE: ISO 15638-16:2014, 4.23, modified — The definition has been editorially updated.]
3.1.27
differential GPS
GNSS (3.1.26) application using only observations from GPS (3.1.25) (Navistar satellite system) and
additional reference point or reference network GPS observations
[SOURCE: ISO 9849:2017, 3.1.5.3]
3.1.28
real-time kinematic positioning
approach for a precise global positioning system (3.1.25), enabling the determination of a range signal
that can be resolved to a precision of less than 10 cm
Note 1 to entry: Facilitated by resolving the number of cycles in which the signal is transmitted and received by
the receiver.
3.1.29
differential GNSS
processing application within mobile GNSS receivers (3.5.27), using difference techniques of GNSS
(3.1.26) observations and additional reference point or reference network GNSS observations
Note 1 to entry: In differential GNSS applications correction data and additional information from a known
reference station are used by mobile rovers, enabling them to improve position accuracy from the 15 m nominal
GNSS accuracy to about 10 cm or less.
[SOURCE: ISO 9849:2017, 3.1.52, modified — The abbreviated term "DGNSS" has been omitted.]
3.1.30
testing of measuring instruments
procedures designed to determine whether a measuring instrument (3.1.7) satisfies requirements in
respect of one or more specified properties under specified conditions
3.1.31
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by measurement standards (3.1.14) and corresponding
indications (3.1.12) with associated measurement uncertainties and, in a second step, uses this
information to establish a relation for obtaining a measurement result (3.1.13) from an indication (3.1.12)
Note 1 to entry: A calibration may be expressed by a statement, calibration function, calibration diagram,
calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicative correction of
the indication with associated measurement uncertainty.
Note 2 to entry: Calibration should not be confused with adjustment of a measuring system (3.1.19), often
mistakenly called “self-calibration”, nor with verification of calibration.
Note 3 to entry: Often, the first step alone in the above definition is perceived as being calibration.
[SOURCE: ISO/IEC Guide 99:2007, 2.39]
3.1.32
comparator
measuring equipment (3.1.8) used in addition to a standard for calibration (3.1.31) of measuring
instruments (3.1.7)
EXAMPLE 1 Comparing a measuring tape (3.4.1) or an EDM (3.5.6) with a bar standard.
EXAMPLE 2 For the determination of the accuracy of an angular scale in a theodolite (3.5.4).
EXAMPLE 3 In photogrammetry (3.1.5), for determining co-ordinates on photographs using stereocomparators.
3.2 Quality of measurement
3.2.1
true value
value which characterizes a quantity perfectly defined in the conditions that exist when that quantity
is considered
Note 1 to entry: It is an ideal value which can be observed only if all causes of measurement error (3.1.17) are
eliminated.
[SOURCE: ISO 772:2011, 7.9]
3.2.2
influence quantity
quantity that, in a direct measurement (3.1.1), does not affect the quantity that is actually measured, but
affects the relation between the indication (3.1.12) and the measurement result (3.1.13)
EXAMPLE Measuring tape (3.4.1) temperature when measuring distances.
[SOURCE: ISO/IEC Guide 99:2007, modified — EXAMPLEs and NOTEs have been omitted; a new
EXAMPLE has been added.]
3.2.3
measurement accuracy
accuracy of measurement
closeness of agreement between a measured quantity value and a true quantity value of a measurand
(3.1.6)
Note 1 to entry: The concept ‘measurement accuracy’ is not a quantity and is not given a numerical quantity
value. A measurement (3.1.1) is said to be more accurate when it offers a smaller measurement error (3.1.17)
Note 2 to entry: The term ‘measurement accuracy’ should not be used for measurement trueness and the term
‘measurement precision’ should not be used for ‘measurement accuracy’ which is related to both these concepts.
Note 3 to entry: ‘Measurement accuracy’ is sometimes understood as agreement between measured quantity
values that are being attributed to the measurand.
[SOURCE: ISO/IEC Guide 99:2007, 2.13]
3.2.4
precision of measurement
closeness of agreement between independent measurement results (3.1.13) obtained under stipulated
conditions
Note 1 to entry: The degree of precision is expressed numerically by the statistical measures of imprecision of
measurements (3.1.1), such as standard deviation (3.2.22), that are inversely related to precision.
6 © ISO 2020 – All rights reserved

3.2.5
accuracy class
class of measuring instruments (3.1.7) or measuring systems (3.1.19) that meet stated metrological
requirements that are intended to keep measurement errors (3.1.17) or instrumental measurement
(3.1.1) uncertainties within specified limits under specified operating conditions
Note 1 to entry: An accuracy class is usually denoted by a number or symbol adopted by convention.
Note 2 to entry: Accuracy class applies to material measures.
[SOURCE: ISO/IEC Guide 99:2007, 4.25]
3.2.6
repeatability of results of measurement
closeness of the agreement between the results of successive measurements (3.1.1) of the same
measurand (3.1.6) carried out under the same conditions of measurement
Note 1 to entry: These conditions are called repeatability conditions.
Note 2 to entry: Repeatability conditions include: the same measurement procedure; the same observer; the
same measuring instrument (3.1.7), used under the same conditions; the same location; repetition over a short
period of time.
Note 3 to entry: Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the
results.
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.15]
3.2.7
reproducibility condition of measurement
condition of measurement (3.1.1), out of a set of conditions that includes different locations, operators,
measuring systems (3.1.19), and replicate measurements on the same or similar objects
Note 1 to entry: The different measuring systems may use different measurement procedures.
Note 2 to entry: A specification should give the conditions changed and unchanged, to the extent practical.
[SOURCE: ISO/IEC Guide 99:2007, 2.24]
3.2.8
systematic measurement error
component of measurement error (3.1.17) that in replicate measurements (3.1.1) remains constant or
varies in a predictable way when the conditions change
Note 1 to entry: A reference quantity value for a systematic reference error is a true quantity value, or a measured
quantity value of a measurement standard (3.1.14) of negligible measurement uncertainty, or a conventional
quantity value.
Note 2 to entry: Systematic measurement error, and its causes, can be known or unknown. A correction (3.2.15)
can be applied to compensate for a known systematic measurement error.
Note 3 to entry: Systematic measurement error equals measurement error minus random measurement error.
[SOURCE: ISO/IEC Guide 99:2007, 2.17]
3.2.9
random error
result of a measurement (3.1.1) minus the mean that would result from an infinite number of
measurements of the same measurand (3.1.6) carried out under repeatability conditions
Note 1 to entry: Random error is equal to error minus systematic measurement error (3.2.8).
Note 2 to entry: Because only a finite number of measurements can be made, it is possible to determine only an
estimate of random error.
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.21]
3.2.10
total measuring error
whole measurement error (3.1.17) which consists of a combination of the random error (3.2.9) and the
systematic error (3.2.8)
3.2.11
closing error
error of closure
amount by which the value of one or more quantities obtained by surveying operations fails to agree
with a fixed or theoretical value of the same quantities
Note 1 to entry: In traversing (3.6.39), this can, for example, be the amounts by which the computed, but not
adjusted, coordinates of the end measuring point (3.6.50) of a traverse fail to agree with the given coordinates of
that measuring point.
3.2.12
discrepancy
difference between results of duplicate or comparable measures of a quantity; or difference in computed
values of a quantity obtained by different processes using data from the same survey
3.2.13
adjustment calculation
calculation process designed to distribute discrepancies due to the existence of redundant observations
(3.1.15) when measurement (3.1.1) is carried out according to certain rules, for example the least squares
method (3.2.14)
Note 1 to entry: A redundant observation is any observation which exceeds the number of observations which
are necessary for an unambiguous determination of the value of a quantity.
3.2.14
least squares method
obtaining true measurement values by minimizing the sum of the squares of the deviations from the
expected values
Note 1 to entry: Measurements are adjusted so that the sum of the squares of the differences between the
observed and adjusted values are minimized.
3.2.15
correction
value added algebraically to the uncorrected result of a measurement (3.1.1) to compensate for
systematic measurement error (3.2.8)
Note 1 to entry: The correction is equal to the negative of the estimated systematic error.
Note 2 to entry: Since the systematic error cannot be known perfectly, the compensation cannot be complete.
[SOURCE: ISO/IEC Guide 98-3:2008, B.2.23]
3.2.16
arithmetic mean
sum of measured values divided by the number of values
[SOURCE: ISO/IEC Guide 98-3:2008, C.2.19, modified – Notes 1 and 2 to entry has been omitted; the
admitted term "average" has been omitted.]
8 © ISO 2020 – All rights reserved

3.2.17
weight of measurement
number which expresses the degree of confidence in the result of a measurement (3.1.1) of a certain
quantity in comparison with the results of another measurement of the same quantity
EXAMPLE 1 When using different types of measuring instruments (3.1.7).
EXAMPLE 2 Ratio of the reliability of various quantities in adjustment calculations (3.2.14), when determining
co-ordinates in triangulation (3.6.37) nets.
Note 1 to entry: The higher the number, the greater the confidence.
3.2.18
arithmetic weighted mean
sum of the products of each measured value and its weight of measurement (3.2.17) (which can be
positive or zero) divided by the sum of the weights of measurement
3.2.19
dispersion
scatter of the measured values obtained in a set of measurements (3.1.1) of a quantity
3.2.20
range
difference between the greatest and least values of a number of observations (3.1.15)
[SOURCE: ISO 1213-2:2016, 3.173]
3.2.21
variance
for any sample, average of the squares of the deviations from the mean
3.2.22
standard deviation
positive square root of the variance (3.2.21)
Note 1 to entry: For a set of data standard deviation is calculated as the square root of the average of the squares
of the deviations from the mean.
3.2.23
normal distribution
Laplace-Gauss distribution
symmetrical “bell shaped” density distribution which is fully defined by its mean and standard deviation
(3.2.22)
3.2.24
root mean squared error
square root of the mean of the squared differences of measured values and predicted values
Note 1 to entry: In calibration (3.1.31), measured values are compared with given (true) values.
3.2.25
standard error of position
square root of the sum of the squared errors of the coordinates (x and y or East and North) of a point
Note 1 to entry: This error is normally calculated after adjustment.
3.2.26
absolute error
result of a measurement (3.1.1) minus the true value (3.2.1)
[SOURCE: ISO 16577:2016, 3.1]
3.2.27
relative error
method of expressing measurement errors (3.1.17) in which %RE = [(measured value – true value
(3.2.1))/true value] × 100 %
Note 1 to entry: In this definition, over-estimates are positive-going errors, and underestimates are negative-
going errors.
[SOURCE: ISO 23833:2013, 5.4.2.6, modified — The admitted terms "accuracy" and "%RE" have been
omitted.]
3.3 Scales
3.3.1
scale
set of marks, lines or numbers, carried by the indicating device (3.3.9) of a measuring instrument (3.1.7)
Note 1 to entry: It is also used in triangulation (3.6.37) calculations.
3.3.2
spaced scale
field gradation
systematic pattern of marks, of different colours, to permit easy recognition of individual gradations
Note 1 to entry: Levelling staves (3.4.7) are usually provided with spaced scales, for example “E-pattern”.
3.3.3
scale mark
gauge mark
line or other mark on an indicating device (3.3.9) corresponding to one or more defined values of the
quantity measured
3.3.4
scale numbering
ordered set of numbers associated with the scale marks (3.3.3)
Note 1 to entry: ISO 14978:2018, Figure 2 illustrates scale numbering on an analogue straight scale (3.3.1)
3.3.5
scale division
space on a scale (3.3.1) between any two successive scale marks (3.3.3)
Note 1 to entry: For a digital scale, the scale division is the difference between two consecutive numbers.
Note 2 to entry: ISO 14978:2018, Figure 2 illustrates scale divisions on an analogue straight scale.
3.3.6
scale spacing
distance between two successive scale marks (3.3.3)
Note 1 to entry: ISO 14978:2018, Figure 2 illustrates scale spacing on an analogue straight scale (3.3.1).
3.3.7
scale length
length between the first and the last scale marks (3.3.3)
Note 1 to entry: ISO 14978:2018, Figure 2 illustrates scale length on an analogue straight scale (3.3.1).
10 © ISO 2020 – All rights reserved

3.3.8
scale interval
absolute value of the difference between the values corresponding to two successive scale marks (3.3.3)
Note 1 to entry: ISO 14978:2018, Figure 2 illustrates scale interval on an analogue straight scale (3.3.1).
3.3.9
indicating device
set of components of a measuring instrument (3.1.7) intended to indicate the
measured value
[SOURCE: ISO 19970:2017, 3.8, modified — The preferred term "displaying device" has been omitted;
domain information has been added.]
3.3.10
index
fixed or movable part of an analogue indicating device (3.3.9), whose position with reference to the scale
marks (3.3.3) enables an indicated value to be determined
Note 1 to entry: For some measuring equipment (3.1.8), the index is called the “pointer”.
[SOURCE: ISO 14978:2018, 3.5.21]
3.3.11
vernier
device by means of a movable scale (3.3.1) to improve the reading (3.1.16) accuracy of optical distance
and angle readings
Note 1 to entry: The reading device is usually an auxiliary scale movable along the scale to be read.
Note 2 to entry: The reading mark is the zero line on the auxiliary scale.
[SOURCE: ISO 9849:2017, 3.2.43]
3.3.12
scale range
set of values bounded by the extreme indications (3.1.12)
Note 1 to entry: The lower limit of the scale range is not necessarily zero, for example, in the case of an internal
micrometer whose scale (3.1.1) starts at 5 mm.
Note 2 to entry: ISO 14978:2018, Figure 2 illustrates scale range on an analogue straight scale.
[SOURCE: ISO 14978:2018, 3.5.19, modified — Note 2 to entry has been amended.]
3.3.13
measuring interval
measuring range
measurement range
set of values of quantities of the same kind that can be measured by a given measuring instrument (3.1.7)
or measuring system (3.1.19) with specified instrumental uncertainty, under defined conditions
Note 1 to entry: The lower limit of a measuring interval should not be confused with detection limit.
3.3.14
analogue indication
analogue read-out
form of presentation of the indications (3.1.12) of a measured value by means of a scale (3.3.1) and an
index (3.3.10)
3.3.15
digital indication
digital read-out
digital display
form of presentation of the indications (3.1.12) of a measured value by means of figures forming a
number which directly indicates a numerical value
[SOURCE: ISO/IEC Guide 99:2007, 4.7]
3.4 Measuring tools
3.4.1
measuring tape
ribbon of steel or other suitable material which is graduated for measurement (3.1.1) of length
Note 1 to entry: Where a very high degree of accuracy of measurement (3.2.3) is required, tapes of invar are used.
Invar is an alloy of nickel and iron containing about 36 % nickel. Its coefficient of expansion is extremely small
-7
over a wide range of temperatures (11 × 10 ) which is about one-tenth of that of steel.
3.4.2
traverse tape
narrow, long lightweight steel measuring tape (3.4.1) for the measurement (3.1.1) of distances up to 100 m
Note 1 to entry: Traverse tapes offer a means of rapid and accurate measurement of distances. To reduce
their costs, traverse tapes are normally graduated only at 1 m intervals. Near the ends, however, the internal
graduation interval is often 1 mm. For convenience in handling, traverse tapes are almost invariably wound on
special reels from which they can easily be unrolled.
Note 2 to entry: Some traverse tapes are brittle and can therefore easily be damaged.
3.4.3
location tape
measuring tape (3.4.1), usually 20 m, 30 m or 50 m in length, intended primarily for detailed survey
(3.6.75) and site survey (3.6.73)
3.4.4
retractable steel pocket tape
measuring tape (3.4.1) up to 5 m in length, usually graduated in intervals of 1 mm throughout and
provided with an enclosing case
3.4.5
folding rule
graduated and numbered rule for the measurement (3.1.1) of lengths, consisting of two or more lengths
of boxwood or other suitable material, connected by hinged joints
3.4.6
measuring rod
straight rod of suitable material of which one edge is graduated for the measurement (3.1.1) of lengths
3.4.7
levelling staff
levelling rod
level rod
straight bar with a scale on a flat face
Note 1 to entry: The levelling staff can be made of, for example, metal, glass fibre or wood.
Note 2 to entry: The levelling staff is used to measure the vertical distance between a base point and the
horizontal line of sight of a level (3.5.2).
[SOURCE: ISO 9849:2017, 3.1.11]
12 © ISO 2020 – All rights reserved

3.4.8
invar levelling staff
levelling staff (3.4.7) for precise levelling (3.6.4), having an invar strip with gradation lines or code
patterns (bar code)
[SOURCE: ISO 9849:2017, 3.1.11.2, modified — Note 1 to entry has been omitted; the preferred terms
"precise levelling rod" and "invar rod" have been omitted.]
3.4.9
digital levelling staff
levelling staff (3.4.7) for levelling (3.6.4) with a digital level (3.4.10) having a specified code patterns on
a flat surface
[SOURCE: ISO 9849:2017, 3.1.11.1, modified — The preferred term "bar code staff" has been omitted.]
3.4.10
digital level
level (3.5.2) which electronically reads a sequence of code patterns on the levelling staff (3.4.7) by an
image sensor
Note 1 to entry: These measuring instruments (3.1.7) usually include data recording capability. The automation
removes the requirement for the operator to read a scale (3.3.1).
Note 2 to entry: The processing and the display of the results are taken by an integrated computer.
[SOURCE: ISO 9849:2017, 3.1.10.2, modified — In Note 1 to entry, “measuring” has been inserted before
“instruments”.]
3.4.11
straightedge
straight bar of suitable material which provides a straight line for the determination of straightness or
flatness
3.4.12
square
equipment for marking out or setting out (3.1.2) a right angle
3.4.13
measuring wedge
wedge shaped measuring device for the measurement (3.1.1) of distances between two surfaces or points
Note 1 to entry: Measuring wedges usually have a slope of 1:10. They are often used for the measurement of joints.
3.4.14
feeler gauge
thin strip of metal of known thickness that can be inserted into a joint gap for the measurement (3.1.1)
of clearances or into a crack to determine its width
3.4.15
sliding calipers
slide gauge
length measuring device consisting of two shanks of which one is in a fixed position and the other can
be moved along a scale (3.3.1) on which the distance between the shanks can be read with the aid of an
index (3.3.10) or a vernier (3.3.11)
3.4.16
micrometer screw
measuring device whose measuring length is provided with a scale (3.3.1) with thread transmission
3.4.17
spirit level
bubble level
device for indicating or checking horizontal or vertical planes, which consists of one or more sealed
tubes made of glass containing a liquid and a trapped air bubble, mounted in a frame
[SOURCE: ISO 6707-1:2017, 3.5.3.19, modified — The preferred term "bubble level" has been added.]
3.4.18
circular level
circular, flat bottomed spirit level (3.4.17) with the liquid under a slightly convex glass face with a circle
mark at the centre
Note 1 to entry: A circular level is used to level a surface in all directions across a plane.
Note 2 to entry: The graduation is normally a circle (3.5.22) of approximately the same diameter as the bubble. In
special cases the graduation consists of a number of concentric circles. Circular levels are normally used when a
high degree of precision is not required.
[SOURCE: ISO 9849:2017, 3.2.16.1, modified — The preferred terms "bull's eye level", "box bubble" and
"circular bubble" have been omitted; note 1 to entry has been editorially updated.]
3.4.19
tubular level
spirit level (3.4.17) with a tube which is barrel-shaped internally and graduated on its upper surface
(level gradation), fixed into a metal holder and fitted with adjusting screws
Note 1 to entry: A tubular level is often built and used for high precision levelling (3.6.4) in the direction of the tube.
[SOURCE: ISO 9849:2017, 3.2.16.2, modified — “tubular glass vial” has been replaced by “tube”.]
3.4.20
vial sensitivity
angle through which the tube of a spirit level (3.4.17) must be tilted to cause a displacement of the bubble
over one scale (3.3.1) spacing
Note 1 to entry: The angle is normally 2 mm of the scale usually engraved on tubes which can be viewed directly.
3.4.21
electronic level
inclinometer
tiltmeter
instrument which detects inclination or changes of inclination under the influence of gravity by the use
of electronic sensors
[SOURCE: ISO 9849:2017, 3.1.10.3]
3.4.22
optical square
compact, hand-held instrument that enables the observer by mirrors or prisms to view a point straight
ahead as well as one perpendicular to it, and thus to set-out a right angle on the ground
3.4.23
plumb bob
conical device, suspended by a cord, by means of which a point can be projected vertically
Note 1 to entry: Plumb bobs are suitable only for rough centring of measuring instruments (3.1.7) over a point.
14 © ISO 2020 – All rights reserved

3.4.24
position piece
ancillary equipment (3.1.9) to facilitate an accurate indication of a measuring point (3.6.50)
Note 1 to entry: Examples of measuring points are corner points or points on the objects to be measured.
3.4.25
optical micrometer
reading device which facilitates the improvement of the reading (3.1.16) accuracy
Note 1 to entry: A major application is the coincidence micrometer to optically read angles, distances and other
scales with a high accuracy.
[SOURCE: ISO 9849:2017, 3.2.29.3]
3.4.26
inclinometer
system for monitoring displacements across a measuring line by means of inclination measurements
(3.6.34) in the field
Note 1 to entry: The system essentially consists of an instrument with one or more tilt sensors, a guide tube, a
means to measure the position of the instrument in the guide tube and a read-out device.
Note 2 to entry: Data from inclinometers require evaluation, which can be done using proprietary software or
spreadsheets.
[SOURCE: ISO 18674-3:2017, 3.1]
3.4.27
laser measuring tool
measuring tool (3.1.11) that through the emission of light facilitates measurement (3.1.1) of the distance
between the tool and the object
3.5 Measuring instruments and their parts
3.5.1
telescope
measuring telescope
part of a measuring instrument (3.1.7) that consists of a magnifying optical device in which a line
through the optical centre of the objective lens and the cross hairs define the line of sight
Note 1 to entry: It comprises essentially an objective, a focusing lens (3.5.18) with focusing drive, a reticule
(3.5.17) and an adjustable eyepiece.
Note 2 to entry: In total stations, often, the electronics and other parts of an electro-optical distance meter (3.5.6)
or other devices are placed in the telescope.
[SOURCE: ISO 9849:2017, 3.2.38, modified — In Note 2 to entry, “electronic distance measurement
device (EDM)” has been changed to “electro-optical distance meter”.]
3.5.2
level
levelling instrument
measuring instrument (3.1.7) for measuring differences in height (3.1.24)- by establishing horizontal
lines of sight, comprising as main components a telescope (3.5.1) which can be rotated on a vertical axis
(3.5.15) and a facility for levelling (3.6.4) the line of sight
Note 1 to entry: It can be additionally fitted with a horizontal circle (3.5.22) and/or a parallel plate micrometer
(3.5.23). The reticule (3.5.17) has sometimes stadia hairs for optical distance measurement (3.6.27).
[SOURCE: ISO 9849:2017, 3.1.10, modified — The preferred term "levelling instrument" has been added;
"measuring instrument" has added at the beginning of the definition; note 2 to entry has been omitted.]
3.5.3
water level
hydrostatic level
level (3.5.2) that consists of two or more glass tubes connected by flexible tubing filled with a fluid
whose surfaces in the glass tubes define a reference level (3.1.23)
Note 1 to entry: The glass tubes are usually provided wi
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