ISO/FDIS 21920-3

Geometrical product specifications (GPS) -- Surface texture: Profile

Spécification géométrique des produits (GPS) -- État de surface: Méthode du profil

General Information

• Status: Published
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: ISO/TC 213 - Dimensional and geometrical product specifications and verification
• Drafting Committee: ISO/TC 213/WG 16 - Areal and profile surface texture

RELATIONS

• Revised: ISO 4288:1996 - Geometrical Product Specifications (GPS) -- Surface texture: Profile method -- Rules and procedures for the assessment of surface texture
• Effective Date: 09-May-2020

Standards Content (sample)

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 21920-3
ISO/TC 213
Geometrical product specifications
Secretariat: BSI
(GPS) — Surface texture: Profile —
Voting begins on:
2021-08-31
Part 3:
Voting terminates on:
Specification operators
2021-10-26
Spécification géométrique des produits (GPS) — État de surface:
Méthode du profil —
Partie 3: Opérateurs de spécification
ISO/CEN PARALLEL PROCESSING
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 21920-3:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
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ISO/FDIS 21920-3:2021(E)
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ii © ISO 2021 – All rights reserved
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ISO/FDIS 21920-3:2021(E)
Contents Page

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

Introduction ..................................................................................................................................................................................................................................v

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

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

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Complete specification operator ......................................................................................................................................................... 2

4.1 Introduction .............................................................................................................................................................................................. 2

4.2 General ........................................................................................................................................................................................................... 2

4.3 General default settings ................................................................................................................................................................... 2

4.4 Default settings based on the specification .................................................................................................................... 3

4.4.1 General rules ....................................................................................................................................................................... 3

4.4.2 Default settings based on Nic or Scn...............................................................................................................4

4.4.3 Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the upper

tolerance limit .................................................................................................................................................................... 5

4.4.4 Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on bilateral

tolerance limits ........................................................................................................................................... ....................... 6

4.4.5 Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the lower

tolerance limit .................................................................................................................................................................... 7

4.4.6 Default settings for Pt .................................................................................................................................................. 7

5 Default attribute values for parameters from ISO 21920-2 .................................................................................... 8

5.1 General ........................................................................................................................................................................................................... 8

5.2 Default attribute values for height parameters and spatial parameters ............................................... 8

5.3 Default attribute values for functions and related parameters..................................................................... 8

5.4 Default attribute values for volume parameters ........................................................................................................ 8

5.5 Default attribute values for feature parameters ........................................................................................................ 9

6 Default units for parameters from ISO 21920-2 .................................................................................................................. 9

6.1 General ........................................................................................................................................................................................................... 9

6.2 Height parameters ............................................................................................................................................................................... 9

6.3 Spatial parameters ............................................................................................................................................................................10

6.4 Hybrid parameters ...........................................................................................................................................................................10

6.5 Material ratio functions and related parameters ...................................................................................................10

6.6 Volume parameters ..........................................................................................................................................................................11

6.7 Feature parameters ..........................................................................................................................................................................11

Annex A (informative) How to determine specification operators ....................................................................................13

Annex B (informative) Examples of the determination of default settings ...............................................................15

Annex C (informative) Major changes from ISO 4288 ......................................................................................................................23

Annex D (informative) Settings for surface texture evaluation in the absence of a specification .....24

Annex E (informative) Overview of profile and areal standards in the GPS matrix model.......................27

Annex F (informative) Relation with the GPS matrix .......................................................................................................................28

Bibliography .............................................................................................................................................................................................................................29

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ISO/FDIS 21920-3:2021(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 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 213, Dimensional and geometrical product

specifications and verification, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC 290, Dimensional and geometrical product specification and verification, in

accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This first edition of ISO 21920-3 cancels and replaces ISO 4288:1996, which has been technically

revised.
The main changes to ISO 4288:1996 are as follows:
— no distinction between periodic and non-periodic profiles;
— the basis for defaults is the drawing indication;

— the maximum tolerance acceptance rule is the default tolerance acceptance rule;

— for the determination of the profile position, surface defects are considered as part of the specified

surface in the default case.
A list of all parts in the ISO 21920 series can be found on the ISO website.

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 2021 – All rights reserved
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ISO/FDIS 21920-3:2021(E)
Introduction

This document is a geometrical product specification (GPS) standard and is to be regarded as a general

GPS standard (see ISO 14638). It influences chain link C of the chains of standards on profile 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 the specifications made in accordance with this

document, unless otherwise indicated.

For more detailed information of the relation of this document to other standards and the GPS matrix

model, see Annex F.
This document specifies the specification operators according to ISO 17450-2.

Throughout this document, parameters are written as abbreviated terms with lower-case suffixes (as

in Rq) which are used in product documentation, drawings and data sheets.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 21920-3:2021(E)
Geometrical product specifications (GPS) — Surface
texture: Profile —
Part 3:
Specification operators
1 Scope

This document specifies the complete specification operator for surface texture by profile methods.

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 21920-1, Geometrical product specifications (GPS) — Surface texture: Profile — Part 1: Indication of

surface texture

ISO 21920-2, Geometrical product specifications (GPS) — Surface texture: Profile — Part 2: Terms,

definitions and surface texture parameters

ISO 16610-21, Geometrical product specifications (GPS) — Filtration — Part 21: Linear profile filters:

Gaussian filters

ISO 16610-31, Geometrical product specifications (GPS) — Filtration — Part 31: Robust profile filters:

Gaussian regression filters
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 21920-1 and ISO 21920-2 and

the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
setting class
Scn
identifier to label default settings
Note 1 to entry: Specific setting classes are Sc1, Sc2, Sc3, Sc4 and Sc5.

Note 2 to entry: The setting class specifies the relevant column of Tables 2 to 6.

1) Under preparation. Stage at the time of publication: ISO/FDIS 21920-1:2021.
2) Under preparation. Stage at the time of publication: ISO/FDIS 21920-2:2021.
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ISO/FDIS 21920-3:2021(E)
4 Complete specification operator
4.1 Introduction

For non-explicitly specified specification elements (see ISO 21920-1) and often-used specification

operators, default settings are used. Default settings should not be expected to ensure correlation with

any particular workpiece function.

The advantage of the default specification operators given in 4.3 and 4.4 is to simplify the drawing

indications.
4.2 General

The complete specification operator (see ISO 17450-2) consists of all the operators required for an

unambiguous specification. It consists of an ordered full set of unambiguous specification operations

in an unambiguous order. For profile surface texture, the complete specification operator defines all

setting elements.

The basis for the default settings is the drawing indication according to ISO 21920-1. For R-parameters

either the setting class or the profile L-filter nesting index shall be specified. For W-parameters either

the setting class or the profile S-filter nesting index shall be specified.

For the R-parameters Ra, Rq, Rz, Rp, Rv, Rzx and Rt, and for Pt, all default settings can be specified by

the specification of the tolerance limit, see 4.4.3 to 4.4.6.

A flowchart illustrating the general way to determine the specification operators is given in Annex A.

Examples for the determination of default settings are given in Annex B. Annex C provides an overview

of the most important changes in the determination of the default settings according to this document

in relation to ISO 4288. A recommendation for the selection of settings in the absence of a specification

is given in Annex D. Annex E provides an overview of the profile and areal standards in the GPS matrix

model.
NOTE 1 There is no distinction between periodic and non-periodic profiles.

NOTE 2 This document describes specification operators. For the verification, the following applies: “the

verification operator is the physical implementation of the specification operator. It may have exactly the same

operations in the same order, in which case the method uncertainty is zero, or it may have different operations

or perform the operations in a different order, in which case the method uncertainty is not zero.” [SOURCE:

ISO 8015:2011, 5.10.1]
NOTE 3 There are no defaults for electromagnetic profiles.
4.3 General default settings

When specifying surface texture by the profile method the surface is the toleranced feature. Therefore,

the profile direction and the profile position are an integral part of the specification. Surface

imperfections and surface defects are part of the specified surface and shall be taken into account when

determining profile locations, if not otherwise stated.

The general default settings given in Table 1, independent of the specified parameter type, shall be

implemented.

NOTE Considering surface imperfections and surface defects as part of the specified surface is a change

from ISO 4288.
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ISO/FDIS 21920-3:2021(E)
Table 1 — General default settings
Criterion Default setting
Procedure of profile
Mechanical profile
extraction

The direction yielding the maximum values of roughness height parameters (perpen-

Profile direction
dicular to the dominant lay direction)

The profile position depends on the tolerance acceptance rule according to ISO 21920-

For the maximum tolerance acceptance rule: location on that part of the surface on

which critical values can be expected. If this location cannot be clearly identified sep-

Profile position
arate traces shall be distributed equally over this part of the surface.
For the 16 % tolerance acceptance rule and for the median tolerance acceptance

rule: uniformly distributed traces shall be taken to represent the entire surface, see

NOTE 1.
Tolerance type Upper tolerance limit
Tolerance acceptance
The maximum tolerance acceptance rule according to ISO 21920-1
rule
Profile S-filter type Gaussian filter according to ISO 16610-21
Gaussian filter according to ISO 16610-21
Profile L-filter type (for
R-parameters) Profile

Exception: The default L-filter for Rk, Rpk, Rvk, Rpkx, Rvkx, Rmrk1, Rmrk2, Rak1,

S-filter type (for W-pa-

Rak2, Rpq, Rmq and Rvq is the robust Gaussian filter, second order according to ISO

rameters)
16610-31, see NOTE 2.
Profile F-operator

Association and removal of the specified form element with total least square, see

association method and
NOTES 3 and 4.
element

NOTE 1 For the verification, this part of the surface can be identified, for example, by visual inspection.

NOTE 2 The change of the default filter type for Rk, Rpk, Rvk, Rpkx, Rvkx, Rmrk1, Rmrk2, Rak1, Rak2, Rpq, Rmq and Rvq

leads to a better elimination of large-scale components and can generate slightly differing values of these parameters from

the values obtained on the basis of ISO 13565-1.
NOTE 3 For the definition of “Association” see ISO 17450-1.

NOTE 4 For a circle, the radius shall also be included in the least square optimization and not held fixed to the nominal

value. The F-operator is applied to the evaluation length.
4.4 Default settings based on the specification
4.4.1 General rules

This subclause defines rules for the default settings based on the specification in addition to the general

default settings.

If several parameters are specified within one graphical symbol, the parameter in the first line shall be

used to select the default settings.

If more than one specification element is specified, the topmost specification element shall be used to

define the column for all non-explicitly specified default settings in Tables 2 to 6.

If a nesting index N not listed in Tables 2 to 6 is specified, a second specification element shall be

specified, for example the setting class Scn, to define the column for all other non-explicitly specified

settings.

If a nesting index N not listed in Tables 2 to 6 is specified, the maximum sampling distance d shall be

is x
N /5, for example if N = 5 µm then the maximum sampling distance d = 1 µm.
is is x
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ISO/FDIS 21920-3:2021(E)

If there is a contradiction between the default profile direction and the default measuring length, the

profile direction shall be respected first.
NOTE See examples in B.1 to B.8.
4.4.2 Default settings based on Nic or Scn

For all R-parameters, except for Ra, Rq, Rz, Rp, Rv, Rzx and Rt, one of the following specifications shall

be given in the drawing indication:
— the profile L-filter nesting index N ; or
— the setting class Scn.

For all W-parameters one of the following specifications shall be given in the drawing indication:

— the profile S-filter nesting index N ; or
— the setting class Scn.

For all P-parameters, except for Pt, one of the following specifications shall be given in the drawing

indication:
— the profile S-filter nesting index N ; or
— the setting class Scn.

This defines the default settings according to the corresponding column in Table 2, which defines the

non-explicitly specified settings.
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ISO/FDIS 21920-3:2021(E)
Table 2 — Default settings based on N or Scn
Setting class
Sc1 Sc2 Sc3 Sc4 Sc5
Profile L-filter nesting index
N (cut-off λ , for R-parame-
ic c
ters)
0,08 0,25 0,8 2,5 8
or profile S-filter nesting
index N (cut-off λ , for W-pa-
ic c
rameters)
0,4 1,25 4 12,5 40
Evaluation length l
Exception: the default evaluation length l for P-parameters is the length of the
specified feature
Profile S-filter nesting index
N (cut-off λ ) 2,5 2,5 2,5 8 25
is s
Maximum sampling distance
d 0,5 0,5 0,5 1,5 5
Maximum nominal tip radi-
us r 2 2 2 5 10
tip
Only for section length parameters
0,08 0,25 0,8 2,5 8
Section length l
Exception: the default section length lsc for section length P-parameters is l /
Number of sections n 5 5 5 5 5

NOTE For P-parameters, there is no difference between Sc1, Sc2 and Sc3 but these columns are retained to keep the

same structure as in Tables 2 to 6.

4.4.3 Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the upper tolerance limit

The default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the specified upper tolerance limit U or

the specified setting class, Scn, are given in Table 3.

If the setting class is specified, it defines the default settings for all non-specified specification elements

even if other specification elements are specified.

Table 3 — Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the upper tolerance limit

Setting class
Sc1 Sc2 Sc3 Sc4 Sc5
Specified parameter Upper tolerance limit (U) of the specified parameter
Rz, µm U ≤ 0,160 0,160 < U ≤ 0,80 0,80 < U ≤ 16,0 16,0 < U ≤ 80 U > 80
Ra, µm U ≤ 0,020 0,020 < U ≤ 0,10 0,10 < U ≤ 2,0 2,0 < U ≤ 10 U > 10
Rp, µm U ≤ 0,060 0,060 < U ≤ 0,30 0,30 < U ≤ 6,0 6,0 < U ≤ 30 U > 30
Rv, µm U ≤ 0,100 0,100 < U ≤ 0,50 0,50 < U ≤ 10,0 10,0 < U ≤ 50 U > 50
Rq, µm U ≤ 0,032 0,032 < U ≤ 0,16 0,16 < U ≤ 3,2 3,2 < U ≤ 16 U > 16
Rzx, µm U ≤ 0,230 0,230 < U ≤ 1,15 1,15 < U ≤ 23,0 23,0 < U ≤ 115 U > 115
Rt, µm U ≤ 0,260 0,260 < U ≤ 1,30 1,30 < U ≤ 26,0 26,0 < U ≤ 130 U > 130
Profile L-filter nesting
index N (cut-off λ ) 0,08 0,25 0,8 2,5 8
ic c
mm
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ISO/FDIS 21920-3:2021(E)
Table 3 (continued)
Setting class
Sc1 Sc2 Sc3 Sc4 Sc5
Specified parameter Upper tolerance limit (U) of the specified parameter
Rz, µm U ≤ 0,160 0,160 < U ≤ 0,80 0,80 < U ≤ 16,0 16,0 < U ≤ 80 U > 80
Evaluation length l ,
0,4 1,25 4 12,5 40
Profile S-filter nesting
index N (cut-off λ ) 2,5 2,5 2,5 8 25
is s
µm
Maximum sampling dis-
tance d 0,5 0,5 0,5 1,5 5
Maximum nominal tip
radius r 2 2 2 5 10
tip
Only for section length parameters, for example Rz, Rp, Rv
Section length l
0,08 0,25 0,8 2,5 8
Number of sections n 5 5 5 5 5

4.4.4 Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on bilateral tolerance limits

The default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the specified bilateral tolerance limits or

the specified setting class, Scn, are given in Table 4.
NOTE Tolerance centre: C = (U + L)/2

Table 4 — Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on bilateral tolerance limits

Setting class
Sc1 Sc2 Sc3 Sc4 Sc5

Specified parameter Tolerance centre (C) of the bilateral tolerance of the specified parameter

Rz, µm C ≤ 0,128 0,128 < C ≤ 0,64 0,64 < C ≤ 12,8 12,8 < C ≤ 64 C > 64
Ra, µm C ≤ 0,016 0,016 < C ≤ 0,08 0,08 < C ≤ 1,6 1,6 < C ≤ 8 C > 8
Rp, µm C ≤ 0,048 0,048 < C ≤ 0,24 0,24 < C ≤ 4,8 4,8 < C ≤ 24 C > 24
Rv, µm C ≤ 0,080 0,080 < C ≤ 0,40 0,40 < C ≤ 8,0 8,0 < C ≤ 40 C > 40
Rq, µm C ≤ 0,026 0,026 < C ≤ 0,13 0,13 < C ≤ 2,6 2,6 < C ≤ 13 C > 13
Rzx, µm C ≤ 0,184 0,184 < C ≤ 0,92 0,92 < C ≤ 18,4 18,4 < C ≤ 92 C > 92
Rt, µm C ≤ 0,208 0,208 < C ≤ 1,04 1,04 < C ≤ 20,8 20,8 < C ≤ 104 C > 104
Profile L-filter nesting
index N (cut-off λ ) 0,08 0,25 0,8 2,5 8
ic c
Evaluation length l
0,4 1,25 4 12,5 40
Profile S-filter nesting
index N (cut-off λ ) 2,5 2,5 2,5 8 25
is s
Maximum sampling dis-
tance d 0,5 0,5 0,5 1,5 5
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ISO/FDIS 21920-3:2021(E)
Table 4 (continued)
Setting class
Sc1 Sc2 Sc3 Sc4 Sc5

Specified parameter Tolerance centre (C) of the bilateral tolerance of the specified parameter

Rz, µm C ≤ 0,128 0,128 < C ≤ 0,64 0,64 < C ≤ 12,8 12,8 < C ≤ 64 C > 64
Maximum nominal tip
radius r 2 2 2 5 10
tip
Only for section length parameters, for example Rz, Rp, Rv
Section length l
0,08 0,25 0,8 2,5 8
Number of sections n 5 5 5 5 5

4.4.5 Default settings for Ra, Rq, Rz, Rp, Rv, Rzx and Rt based on the lower tolerance limit

The default settings for Ra, Rq, Rz, Rp, Rv, Rmax and Rt based on the lower tolerance limits L or the

specified setting class, Scn, are given in Table 5.

Table 5 — Default settings for Ra, Rq, Rz, Rp, Rv, Rmax and Rt based on the lower tolerance limit

Setting class
Sc1 Sc2 Sc3 Sc4 Sc5
Specified parameter Lower tolerance limit (L) of the specified parameter
Rz, µm L ≤ 0,080 0,080 < L ≤ 0,40 0,40 < L ≤ 8,0 8,0 < L ≤ 40 L > 40
Ra, µm L ≤ 0,010 0,010 < L ≤ 0,05 0,05 < L ≤ 1,0 1,0 < L ≤ 5 L > 5
Rp, µm L ≤ 0,030 0,030 < L ≤ 0,15 0,15 < L ≤ 3,0 3,0 < L ≤ 15 L > 15
Rv, µm L ≤ 0,050 0,050 < L ≤ 0,25 0,25 < L ≤ 5,0 5,0 < L ≤ 25 L > 25
Rq, µm L ≤ 0,016 0,016 < L ≤ 0,08 0,08 < L ≤ 1,6 1,6 < L ≤ 8 L > 8
Rzx, µm L ≤ 0,115 0,115 < L ≤ 0,57 0,57 < L ≤ 11,5 11,5 < L ≤ 57 L > 57
Rt, µm L ≤ 0,130 0,130 < L ≤ 0,65 0,65 < L ≤ 13,0 13,0 < L ≤ 65 L > 65
Profile L-filter nesting
index N (cut-off λ ) 0,08 0,25 0,8 2,5 8
ic c
Evaluation length l
0,4 1,25 4 12,5 40
Profile S-filter nesting
index N (cut-off λ ) 2,5 2,5 2,5 8 25
is s
Maximum sampling dis-
tance d 0,5 0,5 0,5 1,5 5
Maximum nominal tip
radius r 2 2 2 5 10
tip
Only for section length parameters, for example Rz, Rp, Rv
Section length l
0,08 0,25 0,8 2,5 8
Number of sections n 5 5 5 5 5
4.4.6 Default settings for Pt

The default settings for Pt based on the specified tolerance limit and tolerance type are given in Table 6.

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ISO/FDIS 21920-3:2021(E)
Table 6 — Default settings for Pt based on the tolerance limit
Setting class
Sc1 Sc2 Sc3 Sc4 Sc5
Upper tolerance limit (U)
U ≤ 0,270 0,270 < U ≤ 1,35 1,35 < U ≤ 27,0 27,0 < U ≤ 135 U > 135
Specified parameter
Centre (C) of the bilateral tolerance limits
C ≤ 0,216 0,216 < C ≤ 1,08 1,08 < C ≤ 21,6 21,6 < C ≤ 108 C > 108
Pt, µm
Lower tolerance limit (L)
L ≤ 0,135 0,135 < L ≤ 0,68 0,68 < L ≤ 13,5 13,5 < L ≤ 68 L > 68
Evaluation length le Length of the specified feature
Profile S-filter nesting
index N (cut-off λ ) 2,5 2,5 2,5 8 25
is s
Maximum sampling dis-
tance d 0,5 0,5 0,5 1,5 5
Maximum nominal tip
radius r 2 2 2 5 10
tip

NOTE In this table, there is no difference between Sc1, Sc2 and Sc3 but these columns are retained to keep the same

structure as in Tables 2 to 6.
5 Default attribute values for parameters from ISO 21920-2
5.1 General

Attribute values are necessary for the calculation of some parameters. The default attribute values are

given in 5.2 to 5.5.

For parameters with necessary attribute values not listed in 5.2 to 5.5, the attribute values shall be

given in the specification.
NOTE Attributes are given in parenthesis following the parameter name.
5.2 Default attribute values for height parameters and spatial parameters

The default attribute values for height parameters and spatial parameters are given in Table 7.

Table 7 — D
...