oSIST prEN ISO 5459:2018

SLOVENSKI STANDARD
oSIST prEN ISO 5459:2018
01-januar-2018
6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND*36*HRPHWULMVNRWROHULUDQMH
5HIHUHQFHLQVLVWHPLUHIHUHQF,62',6
Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum
systems (ISO/DIS 5459.2:2017)
Geometrische Produktspezifikation (GPS) - Geometrische Tolerierung - Bezüge und
Bezugssysteme (ISO/DIS 5459.2:2017)
Spécification géométrique des produits (GPS) - Tolérancement géométrique -
Références spécifiées et systèmes de références spécifiées (ISO/DIS 5459.2:2017)
Ta slovenski standard je istoveten z: prEN ISO 5459
ICS:
17.040.10 Tolerance in ujemi Limits and fits
17.040.40 6SHFLILNDFLMDJHRPHWULMVNLK Geometrical Product
YHOLþLQL]GHOND*36 Specification (GPS)
oSIST prEN ISO 5459:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 5459:2018

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oSIST prEN ISO 5459:2018
DRAFT INTERNATIONAL STANDARD
ISO/DIS 5459.2
ISO/TC 213 Secretariat: BSI
Voting begins on: Voting terminates on:
2017-11-20 2018-01-15
Geometrical product specifications (GPS) — Geometrical
tolerancing — Datums and datum systems
Spécification géométrique des produits (GPS) — Tolérancement géométrique — Références spécifiées et
systèmes de références spécifiées
ICS: 17.040.10; 01.100.20
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 5459.2:2017(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2017

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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2017 – All rights reserved

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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(E)
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 7
5 Datum system basics . 10
5.1 Role of datum system . 10
5.2 Concepts . 10
5.2.1 Introduction . 10
5.2.2 Associated feature in link with a datum system . 10
5.2.3 Situation features of associated feature . 11
5.2.4 Datum used to constrain orientation or location of other ideal features . 12
5.2.5 Operations and types of features in the process to establish a datum . 12
5.2.6 Consideration for indication of datum system . 14
6 Datum feature indication . 14
6.1 Datum feature indicator . 14
6.2 Datum feature identifier . 15
6.3 Identification of a single feature as datum feature . 15
6.4 Completeness of datum feature . 17
6.4.1 Generality . 17
6.4.2 Datum features established from a complete feature . 18
6.4.3 Datum features established from a non‐complete feature defined by one or more
datum targets. 18
6.4.4 Datum feature defined as one located restricted feature . 25
6.4.5 Datum feature defined as one unlocated restricted feature . 26
7 Specification of datums and datum systems . 26
7.1 General . 26
7.2 Interdependency to define a partial toleranced feature and partial datum feature . 28
7.3 Datum system indication – Datum section . 29
7.4 Indication of a datum in a datum indicator of a datum section – Datum indicator . 30
7.5 Rules to define associated features from datum features . 31
7.5.1 General . 31
7.5.2 Rule a — Associated feature type . 32
7.5.3 Rule b — Dimension of an associated feature . 34
7.5.4 Rule c — Material constraints for associated feature . 35
7.5.5 Rule d — Constraint between associated features in a common datum . 36
7.5.6 Rule e — Constraint between associated features in a datum system . 36
7.6 Locked or released degrees of freedom for the members of its datum system . 42
7.7 Special indications for common datum . 45
7.8 Identifications of situation feature on technical product documentation . 46
7.9 Degrees of freedom indication in relation with a datum system . 47
7.10 Establishment of a coordinate system from a datum system . 48
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7.11 Application of Ⓜ, Ⓛ and Ⓟ modifiers in a datum indicator . 49
8 Specification operator for datum . 51
8.1 Introduction. 51
8.2 ISO default specification operator for datum . 51
8.2.1 For association . 51
8.2.2 For filtration . 52
8.3 Special specification operator for datum . 53
8.3.1 General . 53
8.3.2 Filtration specification elements for datum . 54
8.3.3 Association specification elements for datum . 55
8.4 Drawing‐specific default for datum . 57
Annex A (informative) Association for datums . 58
Annex B (informative) Invariance classes . 65
Annex C (informative) Indication and meaning of datum systems for some examples . 67
Annex D (normative) Datum feature indicator for threads . 93
Annex E (informative) Examples of a datum system or a common datum established with
contacting features. 95
Annex F (informative) Examples of a datum system established from datum targets . 100
Annex G (informative) Filter symbols and attached nesting index . 105
Annex H (normative) Relations and dimensions of graphical symbols . 106
Annex I (informative) Former practice . 107
Annex J (informative) Relationship to the GPS matrix model . 108
Bibliography . 110


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oSIST prEN ISO 5459:2018
ISO/DIS 5459.2:2017(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 (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 on 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 the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
This third edition cancels and replaces the second edition (ISO 5459:2011), which has been technically
revised with the following main changes:
 the default association criteria has been changed by defining only one independently to the shape
of the nominal integral feature;
 the representation and indication to identify the plane, the straight line and the point of a datum
system, have been introduced;
 the default filtration method is now defined;
 it is allowed to change default filtration and association methods;
 it is allowed to define a coordinate system from a datum system.

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oSIST prEN ISO 5459:2018
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Introduction
ISO 5459 is a geometrical product specification (GPS) standard and is to be regarded as a general GPS
standard (see ISO 14638). It influences the chain links A, B and C of the chain of standards on size,
orientation, location, run‐out, profile surface texture and areal surface texture.
The ISO GPS matrix model given in ISO 14638 gives an overview of the ISO GPS system of which this
document is a part. The fundamental rules of ISO GPS given in ISO 8015 apply to this document and the
default decision rules given in ISO 14253‐1 apply to specifications made in accordance with this
standard unless otherwise indicated.
For more detailed information of the relation of this document to the GPS matrix model, see Annex I.
For the definitive presentation (proportions and dimensions) of symbols for geometrical tolerancing,
see ISO 7083.
This document provides tools to express location or orientation constraints, or both, for a tolerance
zone. It does not provide information about the relationship between datums or datum systems and
functional requirements or applications.
Former practice of datums is given in Annex H.
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oSIST prEN ISO 5459:2018
DRAFT INTERNATIONAL STANDARD ISO/DIS 5459:2017(E)

Geometrical product specification (GPS) — Geometrical
tolerances — Datum and datum systems
1 Scope
This document specifies terminology, rules and methodology for the indication and understanding of
datums and datum systems in technical product documentation. This document also provides
explanations to assist the user in understanding the concepts involved.
This document defines the specification operator (see ISO 17450‐2) used to establish a datum or a
datum system. The verification operator (see ISO 17450‐2) can take different forms (physically or
mathematically) and is not the subject of this document.
NOTE The detailed rules for maximum and least material requirements for datums are given in ISO 2692.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 128‐24, Technical drawings — General principles of presentation — Part 24: Lines on mechanical
engineering drawings
ISO 1101, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form,
orientation, location and run‐out
ISO 2692, Geometrical product specifications (GPS) — Geometrical tolerancing — Maximum material
requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR)
ISO 17450‐1, Geometrical product specifications (GPS) — General concepts — Part 1: Model for
geometrical specification and verification
ISO 17450‐2, Geometrical product specifications (GPS) — General concepts — Part 2: Basic tenets,
specifications, operators, uncertainties and ambiguities
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1101, ISO 2692, ISO 17450‐1,
ISO 17450‐2 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
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3.1
datum feature
real (non‐ideal) integral feature used for establishing a single datum
Note 1 to entry: A datum feature can be a complete surface, a set of one or more portions of a complete surface, or
a feature of size.
Note 2 to entry: An illustration showing the relations between datum feature, associated feature and datum is
given in Figure 2.
3.2
datum target
specific portion, which is nominally a point, a line segment or an area, taken from a datum feature and
which is totally located on the real workpiece
Note 1 to entry: Where the datum target is a point, a line or an area, it is indicated as a datum target point, a datum
target line or a datum target area, respectively.
3.3
moveable datum target
specific portion, which is nominally a point, a line segment or an area, taken from a datum feature and
which has one freedom of translation along a defined path from other datums established on the real
workpiece
3.4
associated feature (used for datum)
ideal feature which is fitted to the datum feature with a specific association criterion
Note 1 to entry: The type of the associated feature is by default the same as the type of the nominal integral
feature used to establish the datum (for an exception see 7.5.2).
Note 2 to entry: The associated feature for establishing a datum simulates by default the contact between the real
surface of the workpiece and other components.
Note 3 to entry: An illustration showing the relations between datum feature, associated feature and datum is
given in Figure 2.
Note 4 to entry: An associated feature may have the same shape as the nominal integral datum feature or it may be
another shape defined as a contacting feature (see 3.22 and Figure 1).
3.5
datum
set of one or more situation features (point, line, plane) issued from one or more associated integral
features
Note 1 to entry: A datum can be used to locate or orientate an ideal feature (e.g. a tolerance zone, an intersection
plane, an orientation plane, a reference feature or an ideal feature representing for instance a virtual condition).
Note 2 to entry: Datums with maximum material condition or least material condition (see ISO 2692) are not
covered in this document.
Note 3 to entry: When a datum is established, for example, on a complex surface, the datum consists of a plane, a
straight line or a point, or a combination thereof. The modifier [SL], [PL] or [PT], or a combination thereof, can be
attached to the datum identifier to limit the situation feature(s) taken into account relative to the surface.
Note 4 to entry: An illustration showing the relation between datum feature, associated feature and datum is given
in Figure 2.
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Note 5 to entry: Without qualifier, a datum is a single datum or a common datum.
3.6
single datum
datum established from one datum feature taken from one single surface or from one feature of size
Note 1 to entry: The invariance class of a single surface can be complex, prismatic, helical, cylindrical, revolute,
planar or spherical. A set of situation features defining the datum (see Table B.1) corresponds to each type of
single surface.
Note 2 to entry: See the rule in 7.4.
3.7
common datum
datum established from two or more datum features after simultaneous associations without specific
order and with interrelated constraints
Note 1 to entry: To define a common datum, it is necessary to consider the collected surface created by the
identified datum features. The invariance class of a collected surface can be complex, prismatic, helical, cylindrical,
revolute, planar or spherical (see Table B.1).
Note 2 to entry: See the rule in 7.4.
Note 3 to entry: The result of the common datum cannot be considered as a collection of the situation features of
each associated feature. For example a common datum, established from two parallel non‐coaxial cylinders, is a
set of a plane and a straight line contained in the plane. See Examples 1 to 4 in 7.5.6.
3.8
datum system
set of one or more situation features (point, straight line, plane) resulting from one or more datums
established in a specific order from one or more datum features
Note 1 to entry: To define a datum system, it is necessary to consider the collected surface created by the
identified datum features to identify its invariance class (see Table B.1).
Note 2 to entry: A datum system can consist of one common datum or one single datum.
Note 3 to entry: The role of a datum system is described in 5.1.
3.9
datum section
specification element containing one, two or three datum indicators
Note 1 to entry: A datum section can be used as a part of a tolerance indicator, an intersection plane indicator, an
orientation plane indicator, collection plane indicator or a direction feature indicator (see ISO 1101). See Figure 2.
3.10
datum indicator
specification element containing only one datum identifier
Note 1 to entry: See Figure 2.
3.11
datum identifier
label, designating a datum in a datum indicator, which is identical to the datum feature identifier in the
case of a single datum, or which is a sequence of datum feature identifiers separated by an hyphen in
the case of a common datum
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Note 1 to entry: See Figure 2.
3.12
situation feature identifier
label, designating a situation feature (point, straight line or plane) related to a datum
3.13
datum feature identifier
label, defined by one or more capital letters, identifying the nominal integral feature, corresponding to a
datum feature
Note 1 to entry: The same label is also used to identify a single datum.
Note 2 to entry: see Table 1 and Clause 6.
3.14
datum feature indicator
graphical symbol used to define an integral feature as a datum feature and containing a datum feature
identifier
Note 1 to entry: See Table 1 and 5.2.
3.15
primary datum
datum indicated in the first datum indicator of the datum section
Note 1 to entry: A primary datum is not influenced by constraints from other datums (see 7.1).
3.16
secondary datum
datum indicated in the second datum indicator of the datum section
Note 1 to entry: A secondary datum is constrained at least in orientation from the primary datum (see 7.1).
3.17
tertiary datum
datum indicated in the third datum indicator of the datum section
Note 1 to entry: The tertiary datum is constrained at least in orientation from the primary datum and the
secondary datum (see 7.1).
3.18
collected surface
two or more surfaces considered simultaneously as a surface
Note 1 to entry: Table B.1 is used to determine the invariance class of datums or datum systems when using a
collection of surfaces.
Note 2 to entry: Two intersecting planes may be considered simultaneously or sequentially (one after the other).
When the two intersecting planes are considered simultaneously as a single surface, that surface is a collected
surface.
3.19
objective function
objective function for association
formula that describes the goal of association
Note 1 to entry: In this document, the term "objective function" refers to "objective function for association".
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Note 2 to entry: The objective functions are usually named and mathematically described: maximum inscribed,
minimum zone, etc.
3.20
(association) constraint
requirement to establish an associated feature
EXAMPLE Orientation constraint, location constraint, material constraint or intrinsic characteristic
constraint.
3.20.1
orientation constraint
constraint on one or more rotational degrees of freedom between the situation features of associated
feature
3.20.2
location constraint
constraint on one or more translational degrees of freedom between the situation features of associated
feature
3.20.3
material constraint
additional condition to the location of the associated feature, relative to the material of the feature,
while optimizing an objective function
Note 1 to entry: For example, an association constraint can be that all distances between the associated feature
and the datum feature are positive or equal to zero, i.e. the associated feature is outside the material.
3.20.4
intrinsic characteristic constraint
additional requirement applied to the intrinsic characteristic of an associated feature whether it is
considered as fixed or variable
3.21
association criterion
objective function with or without constraints, defined for an association
Note 1 to entry: Several constraints may be defined for an association.
Note 2 to entry: Association results (associated features) may differ, depending upon the choice of association
criterion.
Note 3 to entry: Default association criteria are defined in 8.2.
3.22
contacting feature
ideal feature, with theoretical exact geometry (shape and dimension), different from the nominal
geometry of the integral geometrical feature with which it is in contact
Note 1 to entry: A contacting feature can be used to define a set of one or more datum features, and/or to establish
a datum.
Note 2 to entry: See rule a in 7.5.2.
Note 3 to entry: See Figure 1.
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a) Contacting feature on nominal model b) Contacting feature on real workpiece
Key
1 contacting feature: ideal sphere in contact with the datum feature or the feature under consideration
2 features under consideration: nominal trapezoidal slot (collection of two non‐parallel surfaces)
3 datum feature: real feature corresponding to the trapezoidal slot (collection of two non‐parallel surfaces)
Figure 1 — Example of a contacting feature
3.23
datum coordinate system
cartesian coordinate system established from a datum system
Note 1 to entry: The datum coordinate system can describe some degrees of freedoms, which are locked through
the datum system.
Note 2 to entry: Using a datum coordinate system is optional.
EXAMPLE A datum system defined by only a primary datum, which is a plane, can allow establishing a
non‐unique datum coordinate system, one translation and two rotations be
...