EN ISO 129-1:2019

SLOVENSKI STANDARD
01-december-2019
Tehnična dokumentacija proizvodov - Predstavitev dimenzij in toleranc - 1. del:
Splošna načela (ISO 129-1:2018)
Technical product documentation (TPD) - Presentation of dimensions and tolerances -
Part 1: General principles (ISO 129-1:2018)
Technische Produktdokumentation (TPD) - Angabe von Maßen und Toleranzen - Teil 1:
Grundlagen (ISO 129-1:2018)
Documentation technique de produits - Représentation des dimensions et tolérances -
Partie 1: Principes généraux (ISO 129-1:2018)
Ta slovenski standard je istoveten z: EN ISO 129-1:2019
ICS:
01.110 Tehnična dokumentacija za Technical product
izdelke documentation
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 129-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 01.100.01
English Version
Technical product documentation (TPD) - Presentation of
dimensions and tolerances - Part 1: General principles (ISO
129-1:2018)
Documentation technique de produits - Représentation Technische Produktdokumentation (TPD) - Angabe
des dimensions et tolérances - Partie 1: Principes von Maßen und Toleranzen - Teil 1: Grundlagen (ISO
généraux (ISO 129-1:2018) 129-1:2018)
This European Standard was approved by CEN on 5 August 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, 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: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 129-1:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 129-1:2018 has been prepared by Technical Committee ISO/TC 10 "Technical product
documentation” of the International Organization for Standardization (ISO) and has been taken over as
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 April 2020, and conflicting national standards shall be
withdrawn at the latest by April 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN 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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 129-1:2018 has been approved by CEN as EN ISO 129-1:2019 without any modification.

INTERNATIONAL ISO
STANDARD 129-1
Second edition
2018-02
Technical product documentation
(TPD) — Presentation of dimensions
and tolerances —
Part 1:
General principles
Documentation technique de produits — Représentation des
dimensions et tolérances —
Partie 1: Principes généraux
Reference number
ISO 129-1:2018(E)
©
ISO 2018
ISO 129-1:2018(E)
© ISO 2018
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: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Presentation of dimensions . 3
4.1 Presentation rules . 3
4.1.1 Dimensions . 3
4.1.2 Repeated dimensions . 3
4.1.3 Out of scale dimensions . 3
4.1.4 Auxiliary dimensions . 3
4.1.5 Theoretically exact dimensions . 3
4.1.6 Symmetrical dimensions . 4
4.1.7 Characters and presentation . 4
4.2 Positioning of dimensions . 4
4.3 Units of dimensions . 6
5 Elements of dimensioning — Usage . 6
5.1 General . 6
5.2 Property indicators . 7
5.3 Dimension line . 8
5.4 Terminators and origin presentation .11
5.4.1 Terminators .11
5.4.2 Origin presentation .12
5.5 Extension line .13
5.6 Leader line .17
5.7 Dimensional values .17
5.7.1 Presentation .17
5.7.2 Placement of dimensional values and symbols .17
5.7.3 Special placement of dimensional values and symbols .19
5.8 Alpha numerical characters and symbols representing dimensional values .20
5.8.1 Alpha numerical characters representing dimensional values .20
5.8.2 Symbols added to dimensional values .21
5.9 Tabular dimensioning .21
5.10 Complementary indication .22
6 Presentation of dimensional tolerances .22
6.1 General .22
6.2 Limit deviations .22
6.3 Limit dimensioning .24
7 Presentation of special dimensions .24
7.1 Arrangement of graphical and letter symbols with dimensional values .24
7.2 Diameters .26
7.3 Radii.26
7.3.1 General.26
7.3.2 Dimension location of radius centre .27
7.3.3 Semicircle features .28
7.3.4 Combined radii presentation .28
7.4 Spheres .29
7.5 Between .29
7.6 Arcs, chords and angles .30
7.7 Squares .32
7.8 Equally spaced and repeated features .33
7.8.1 Equally spaced features .33
ISO 129-1:2018(E)
7.8.2 Repeated features .35
7.8.3 Tabulated repeated features .36
7.9 Symmetrical workpieces and views .37
7.10 Presentation of levels .39
7.11 Dimensions of out-of-scale represented features .40
7.12 Auxiliary dimensions .40
7.13 Theoretical exact dimensions .40
7.14 Dimensioning of curved features .40
7.14.1 Curved features defined by radii .40
7.14.2 Curved features defined by coordinate dimensions.41
7.15 Dimensioning of developed views .43
7.16 Dimensioning of thin parts .43
7.16.1 Thickness indication .43
7.16.2 Surface indication .44
7.17 Dimensioning of restricted areas .45
7.17.1 General Rules .45
7.17.2 Dimensioning of restricted areas on surfaces of revolution .45
7.17.3 Dimensioning of restricted areas on other than surfaces of revolution .46
8 Arrangements of dimensions .47
8.1 General .47
8.2 Chain dimensioning .47
8.3 Parallel dimensioning .47
8.4 Running dimensioning .48
8.4.1 General.48
8.4.2 Unidirectional and bidirectional running dimensions .48
8.5 Coordinate dimensioning .52
8.5.1 Cartesian coordinate dimensioning .52
8.5.2 Polar coordinate dimensioning .54
8.6 Combined dimensioning .55
9 Notes and special notations .56
9.1 Flag notes .56
9.2 Indication of textual instructions .58
Annex A (normative) Relations and dimensions of graphical symbols .60
Annex B (informative) Chamfers, countersinks, wedges, cones and screw threads .64
Annex C (informative) Former practice .67
Bibliography .68
iv © ISO 2018 – All rights reserved

ISO 129-1:2018(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 10, Technical product documentation.
This second edition cancels and replaces the first edition (ISO 129-1:2004), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— that this document does not cover the application of dimensioning tolerances has been clarified;
— property indicator, surface indicator, developed length and between symbols have been discussed;
— flag notes and textual instructions have been discussed;
— dimensioning repeated features and restricted areas have been clarified.
A list of all parts in the ISO 129 series can be found on the ISO website.
ISO 129-1:2018(E)
Introduction
This document is intended for all fields of application. See other parts of ISO 129 for information
pertaining to specific application areas.
The principles of tolerancing and the interpretation of tolerance presentations are given in the
ISO 14405 series.
Figures in this document illustrate the rules and are not intended to show complete representations. It
should be understood that third-angle projection could equally well have been used without prejudice
to the principles established.
vi © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 129-1:2018(E)
Technical product documentation (TPD) — Presentation of
dimensions and tolerances —
Part 1:
General principles
1 Scope
This document establishes the general principles for presentation of dimensions and associated
tolerances that apply to 2D technical drawings in all disciplines and trades but which can also be
applied to 3D applications.
This document does not cover the application of dimensional tolerances and their meaning. See
ISO 14405-1 for tolerancing principles. This document can only be used to describe the nominal model
of a drawing, not the non-ideal surface model (skin model) used for tolerancing purposes (for more
information on tolerancing specifications, see the list of GPS standards listed as normative reference or
as bibliography)
Considering the ISO 14405 series, the presentation of tolerance indication is unambiguous when it is
applied to a dimension which is a size and ambiguous when the dimension is not a size.
All rules presented in this document are available for any type of drawing (see ISO 29845).
In addition, this document introduces the concept of property indicators, developed length, between,
surface indicators, flag notes and textual instructions.
NOTE 1 All figures are shown in 2D views only.
NOTE 2 Additional information and details for construction engineering are given in ISO 6284.
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 128-20, Technical drawings — General principles of presentation — Part 20: Basic conventions for lines
ISO 128-22, Technical drawings — General principles of presentation — Part 22: Basic conventions and
applications for leader lines and reference lines
ISO 128-24:2014, Technical drawings — General principles of presentation — Part 24: Lines on mechanical
engineering drawings
ISO 3098 (all parts), Technical product documentation — Lettering
ISO 10209, Technical product documentation — Vocabulary — Terms relating to technical drawings,
product definition and related documentation
ISO 14405 (all parts), Geometrical product specifications (GPS) — Dimensional tolerancing
ISO 81714-1, Design of graphical symbols for use in the technical documentation of products — Part 1:
Basic rules
ISO 129-1:2018(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10209 and the following apply.
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/
3.1 Elements of dimensioning
3.1.1
centre line
line or set of two perpendicular lines used to represent a median feature, e.g. an axis or a centre plane
3.1.2
dimension line
straight or curved line with terminators at each end or origin and terminator at each end, indicating
the size of a feature or the extent of a feature or between two features, or between a feature and an
extension line (3.1.3), or between two extension lines
3.1.3
extension line
line which is an extension of a feature outline or of a centre line (3.1.1)
3.1.4
origin symbol
circle indicating the start of running dimensioning or coordinate dimensioning
3.2 Dimensions
3.2.1
angular dimension
angle of an angular feature of size or angle between two features
Note 1 to entry: In mechanical engineering drawings, angular dimensions are classified as angular sizes or
angular distances; see ISO 14405-2.
3.2.2
dimensional value
nominal numerical value expressed in a specific unit relevant to a linear or angular dimension (3.2.4, 3.2.1)
Note 1 to entry: The tolerance limits and/or permissible deviations are applied to the dimensional value.
3.2.3
developed length
initial length of material prior to forming, e.g. by bending
3.2.4
linear dimension
linear size of a feature of size or a linear distance between two features
Note 1 to entry: In mechanical engineering drawings, linear dimensions are classified as linear sizes or linear
distances; see ISO 14405-2.
3.2.5
property indicator
symbol used to define the shape of a feature or property of an entity composed by several features
2 © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
4 Presentation of dimensions
4.1 Presentation rules
4.1.1 Dimensions
Only the dimensions necessary to unambiguously define the nominal geometry (nominal model) shall
be presented. Each dimension shall be presented only once by using a dimension line, a dimension value
preceded, and if necessary, by a property indicator. When there is a need to repeat the presentation of a
dimension, auxiliary dimensions may be used.
Dimensional values indicated in decimal notation, shall use a comma as the decimal marker.
Unless otherwise specified, dimensions shall be indicated for the finished state of the dimensioned
feature.
The text of all dimensions, graphical symbols and annotations shall be indicated above the dimension
line and read from the bottom. When the text of a dimension, symbol or annotation is presented
vertically, it shall read from the right. The determination of orientation is based on the centre of the
dimension, symbol or annotation.
Dimensions alone are not sufficient to define the requirements of a product. Dimensions shall be used
with other specification techniques as applicable, e.g. general tolerances, geometrical tolerancing or
surface texture requirements.
4.1.2 Repeated dimensions
When a feature is repeated on the drawing, it is possible to simplify the indication of its dimension on
the drawing by indicating:
— on one instance of the feature, the nominal dimension (with a property indicator symbol if
appropriate), preceded by the associated number of repetition, followed by a multiplication symbol
(×) and a space (e.g. 2× ⌀18) (see Figure 10). To avoid confusion, it is possible to identify each member
of the repetition using a reference identifier (e.g. letter or symbol) (see Figure 64);
— a nominal dimension (with a property indicator symbol if appropriate) above a reference line, which
is attached to each member of the repetition (see Figures 49 and 50).
4.1.3 Out of scale dimensions
By default, a dimension line is drawn to the scale of the drawing. In exceptional cases, in 2D drawing
only, when the dimension value does not correspond to its dimension scale value (out-of-scale features),
the dimension value shall be marked by underlining the dimensional value (see 7.11 and Figure 70).
4.1.4 Auxiliary dimensions
A dimension value can be defined as a dimension for information purposes only. In this case, the
dimension value shall be placed into parenthesis, ( ). This kind of dimension is called an auxiliary
dimension (see 7.12 and Figures 65 and 66).
4.1.5 Theoretically exact dimensions
When a dimension value shall be considered as a theoretical exact dimension and not associated
with general ± tolerancing or not an auxiliary dimension, it shall be placed in a rectangular frame (in
accordance with ISO 1101, 7.13 and Figure 71).
ISO 129-1:2018(E)
4.1.6 Symmetrical dimensions
When the design of a part has one or more symmetries, it is possible to represent a portion of the part
which can allow reconstructing the complete part by symmetry (see 7.9). In this case, the dimensions,
shown only on the portion and the dimension line between two symmetrical features, are indicated
from the feature shown on the portion with a termination and cross perpendicularly the axis of
symmetry without termination (see Figures 65 and 66).
4.1.7 Characters and presentation
Characters on drawings shall be in accordance with the ISO 3098 series.
There shall be only one character height for dimension and tolerance presentation for a specific
drawing.
A space shall separate the elements of the dimension indicator (see Figures A.3 and A.4).
The dimension value and the lower deviation shall be at the same distance from the dimension line (see
Examples 1 and 2).
When upper and lower tolerance limits are presented in two separate lines (e.g. limit deviations,
dimension limit values), the decimal marker of the upper and lower shall be aligned. When a tolerance
limit is not shown with a decimal marker, the remaining digits shall be aligned as if the decimal marker
had been displayed (see Examples 1 and 2).
Trailing zeros may or may not be presented:
Example 1 Example 2
+0,20 0
2× 55 −0,15 2× 55 −0,15
Deviations shall always be presented with a “+” or “−” sign as appropriate, unless the value is zero, in
which case, no sign shall be presented (see Example 2).
For tolerances attached to a dimension displayed in accordance with ISO 286-1, it is not necessary to
express the values of the deviations unless they are needed (see Figure 1).
Figure 1
4.2 Positioning of dimensions
Dimensions shall be placed in a view or section which shows the relevant feature(s) most clearly (see
Figure 2).
4 © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
Figure 2
Dimension lines for internal features and dimension lines for external features shall, wherever possible,
be arranged and indicated in separate groups of dimensions to improve readability (see Figure 3).
Figure 3
Where several features or objects are depicted in close proximity, their relative dimensions shall be
grouped together, separately, for ease of reading (see Figure 4).
Whenever possible, dimensions should not be placed within the contour of the depicted item.
Dimensioning of hidden features is not recommended and should be avoided unless absolutely necessary
and completely unambiguous.
ISO 129-1:2018(E)
Figure 4
4.3 Units of dimensions
For linear units, the predominant unit on a drawing may be specified on the drawing or in an associated
document and the unit omitted from the individual dimensions.
For angular dimensions, the units shall always be specified with the individual dimensions (see Figure 7
and Figures 34 to 37).
Any dimensions expressed in a different unit of measure shall indicate that unit of measure.
5 Elements of dimensioning — Usage
5.1 General
Various elements of dimensioning are illustrated in Figure 5.
6 © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
Key
1 dimension line
2 nominal dimension value
3 terminator (in this case, an arrowhead)
4 extension line
5 leader line
6 reference line
7 origin symbol
8 property indicator
9 reference letter
Figure 5
5.2 Property indicators
Property indicator symbols (see Table 1) may be used to describe the shape of the feature and the
type of associated dimension. The symbol shall precede the dimension without a space (see figures
referenced in Table 1).
No property indicator is required for the presentation of
— linear dimensions between two parallel planes (see Figure 9), or two parallel straight lines (see
Figure 41), or
— angular dimensions between two intersecting planes (see Figures 7 and 59) or two intersecting
straight lines.
ISO 129-1:2018(E)
Table 1
Property Example of pres-
Description Associated property
indicator symbol entation
Cylindrical feature or circular
Diameter Figures 2, 6 and 10
feature described by its diameter.
Cylindrical feature or circular
Radius Figures 8 and 44
feature described by its radius.
Square feature with four equal
Square angles and four equal sides Figures 4, 55 to 57
described by its side dimension.
Spherical Spherical feature described by its
Figure 51
diameter diameter.
Spherical Spherical feature described by its
Figure 52
radius radius.
Curvilinear dimension of non-flat
Arc length Figures 8, 53 and 54
feature (e.g. arc length).
Thickness Two offset features defined by its
Figure 78
(of thin objects) thickness.
Depth Depth of a hole or internal feature. Figures 39 and 41
Cylindrical hole with a flat
Cylindrical
bottom described by its diameter Figure 39
counterbore
and depth.
Circular chamfer described by
Countersink Figure 40
a diameter and angle.
Developed Length of feature prior to
Figure 77
length bending or forming.
Indication of the extent of a
restricted area, used in
Between Figures 54 and 81
conjunction with reference
letters.
5.3 Dimension line
Dimension lines shall be indicated as continuous narrow lines according to ISO 128-20.
Dimension lines shall be indicated in the case of:
— linear dimension:
— which is a size of a feature of size indicated by a single dimension line (see Figures 6 and 27);
— which is radius generated from the geometrical centre of the circle of which the arc is part and
leading to the outline of the arc (see Figure 8);
— which is a distance between two features or an extent of restricted area parallel to the length
to be dimensioned (see Figures 10 and 83);
— angular dimensions or dimensions of an arc as a circular arc around the vertex of the angle or the
centre of the arc (see Figures 7 and 8).
Where space is limited, dimension lines may be extended past the extension lines and the arrowheads
placed outside of the extension lines and reversed (see Figure 2).
8 © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
Figure 6
Figure 7
Figure 8
Where the feature is shown broken, the corresponding dimension line shall be shown unbroken (see
Figure 9).
ISO 129-1:2018(E)
Figure 9
Dimension lines of circular features may be indicated obliquely through the centre of the feature (see
Figure 10).
Intersection of dimension lines with any other line should be avoided, but where intersection is
unavoidable, they shall be shown unbroken (see Figure 10).
Centre lines and the outlines of a feature shall not be used as dimension lines.
Figure 10
Dimension lines may be shown not in full, when:
— dimensions of diameters are indicated (see Figure 11);
— a part of a symmetrical feature is drawn in a view or section (see Figures 65 and 67);
— the reference feature for dimensioning is not on the drawing sheet and there is no need for its
presentation (see Figure 45, R140);
— simplified running dimensioning is used [see Figure 90 b)].
10 © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
Figure 11
5.4 Terminators and origin presentation
5.4.1 Terminators
Terminators shall be shown according to one of the following representations (see Figure 12):
a) arrowheads: when an arrowhead is shown, it shall be one of the following types (only one type of
arrowhead shall be used on a single drawing or set of drawings):
1) closed 30° filled, Figure 12 a);
2) closed 30° unfilled, Figure 12 b);
3) open 30°, Figure 12 c);
4) open 90°, Figure 12 d);
b) oblique stroke, Figure 12 e) and f);
c) point, Figure 12 g).
Figures 12 c) and d) terminators shall not be used for mechanical engineering purposes.

ISO 129-1:2018(E)
a) closed 30° filled b) closed 30°unfilled
c)  open 30° d)  open 90°
e)  oblique stroke f)  oblique stroke between arrows
g)  point between arrows
Figure 12
The size ratios of the terminators illustrated in Figure 12 shall be in accordance with Annex A.
Where space is available, the arrowhead terminators shall be shown between the extension lines (see
Figure 14). Where space is limited, the arrowhead termination may be
— shown outside of the extension lines on an extended dimension line (see Figure 26, dimension 1,5), or
— substituted with either points or oblique strokes (see Figure 26, dimension 6), or
— substituted by the use of an opposing arrowhead or other terminator from another dimension line
(see Figure 26, dimension 3, Figure 83 and Figure 100, dimension 5).
5.4.2 Origin presentation
The origin symbol may be used for
— the origin for running dimensioning (see 8.4), or
— the origin of a coordinate system for coordinate dimensioning (see 8.5).
The origin symbol shall be indicated on the dimension line at the location where a specific dimension or
multi dimensions start (see Figures 13 and 96).
The size ratios of the origin circle illustrated in Figure 13 shall be in accordance with Annex A.
NOTE The origin symbol does not change the meaning of dimensional tolerances and does not function as
a datum.
Figure 13
12 © ISO 2018 – All rights reserved

ISO 129-1:2018(E)
5.5 Extension line
Extension lines shall be drawn as continuous narrow lines according to ISO 128-20.
Extension lines should not be drawn between views and should not be drawn parallel to the direction
of hatching.
Extension lines shall extend approximately eight times the line width beyond their associated
dimension line.
Extension lines should be drawn perpendicular to the corresponding physical length (see Figures 5, 6,
11, 14 and 15).
For circular features, the extension line shall be drawn as a continuation of the feature shape (see
Figure 43, ⌀60).
It is permissible to have a gap, eight times the extension line width, between the feature and the
beginning of the extension line (see Figure 15). Gaps can be used with any terminator.
The centre line or outline of a feature or their extensions may be used in place of an extension line (see
Figure 10).
Where common extension lines are shown, i.e. between repeated features, they should be considered to
be coincident (see Figure 21).
Figure 14
Figure 15
The extension lines may be drawn oblique to the feature but shall be parallel to each other (see
Figure 16).
ISO 129-1:2018(E)
Figure 16
When dimensioning, intersecting projected contours of outlines shall extend approximately eight times
the line width beyond the point of intersection (see Figure 17).
Figure 17
In the case of projected contours of transitions and similar features, the extension lines apply at the
point of intersection of the projection lines (see Figure 18).
14 © ISO 2018 – All rights reserved

SIST EN ISO 12
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