SIST EN 9300-110:2018

SLOVENSKI STANDARD
01-oktober-2018
Aeronavtika - LOTAR - Dolgotrajno arhiviranje in iskanje digitalne tehnične
dokumentacije o izdelkih, kot so podatki o 3D, CAD in PDM - 110. del: CAD
mehanske 3D eksplicitne informacije o geometriji
Aerospace series - LOTAR -LOng Term Archiving and Retrieval of digital technical
product documentation such as 3D, CAD and PDM data - Part 110: CAD mechanical 3D
Explicit geometry information
Luft- und Raumfahrt - LOTAR - Langzeitarchivierung und Bereitstellung digitaler
technischer Produktdokumentationen beispielsweise 3D CAD und PDM Daten - Teil 110:
Explizite Geometrie
Série aérospatiale - LOTAR - Archivage long terme et récupération des données
techniques produits numériques telles que CAD 3D et PDM - Partie 110 : Archivage long
terme et récupération des informations CAO
Ta slovenski standard je istoveten z: EN 9300-110:2018
ICS:
01.110 Tehnična dokumentacija za Technical product
izdelke documentation
35.240.10 Računalniško podprto Computer-aided design
snovanje (načrtovanje, (CAD)
oblikovanje) (CAD)
35.240.30 Uporabniške rešitve IT v IT applications in information,
informatiki, dokumentiranju in documentation and
založništvu publishing
49.020 Letala in vesoljska vozila na Aircraft and space vehicles in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 9300-110
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2018
EUROPÄISCHE NORM
ICS 01.110; 35.240.30; 49.020
English Version
Aerospace series - LOTAR -LOng Term Archiving and
Retrieval of digital technical product documentation such
as 3D, CAD and PDM data - Part 110: CAD mechanical 3D
Explicit geometry information
Série aérospatiale - LOTAR - Archivage long terme et Luft- und Raumfahrt - LOTAR - Langzeit-Archivierung
récupération des données techniques produits und -Bereitstellung digitaler technischer
numériques telles que 3D, CAO et PDM - Partie 110 : Produktdokumentationen, wie zum Beispiel von 3D-,
Données de géométrie 3D explicite en CAO mécanique CAD- und PDM-Daten - Teil 110: Eindeutige 3D-
Geometrieinformationen für mechanische CAD-Teile
This European Standard was approved by CEN on 25 September 2017.

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

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 9300-110:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Foreword . 4
1 Scope . 5
2 Normative references . 6
3 Terms and definitions . 6
4 Applicability . 7
5 Business specifications for the long term archiving and retrieval of CAD mechanical
3D explicit geometry information . 7
6 Essential information of explicit geometry . 10
7 Definition of core model for an explicit geometry . 11
8 Verification rules of explicit geometry . 11
9 Validation rules of an explicit geometry . 16
(informative) Description of use cases for long term archiving and retrieval of CAD
3D explicit geometry . 20
(informative) Definition of explicit 3D shape as advanced boundary representation
according ISO 10303-514 . 26
(informative) Definition of tessellated 3D shape according ISO 10303-42 . 29
(informative) Recommended verification rules level 1 and level 2 . 32
(informative) Illustration of qualification reports . 36
(informative) Illustration of CAD 3D geometry validation properties . 37

European foreword
This document (EN 9300-110:2018) has been prepared by the Aerospace and Defence Industries
Association of Europe - Standardization (ASD-STAN).
After enquiries and votes carried out in accordance with the rules of this Association, this Standard has
received the approval of the National Associations and the Official Services of the member countries of
ASD, prior to its presentation to CEN.
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 December 2018, and conflicting national standards
shall be withdrawn at the latest by December 2018.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Foreword
This standard was prepared jointly by AIA, ASD-STAN, PDES Inc and the PROSTEP iViP Association.
The PROSTEP iViP Association is an international non-profit association in Europe. For establishing
leadership in IT-based engineering it offers a moderated platform to its nearly 200 members from
leading industries, system vendors and research institutions. Its product and process data
standardization activities at European and worldwide levels are well known and accepted. The
PROSTEP iViP Association sees this standard and the related parts as a milestone of product data
technology.
PDES Inc is an international non-profit association in USA. The mission of PDES Inc is to accelerate the
development and implementation of ISO 10303, enabling enterprise integration and PLM
interoperability for member companies. PDES Inc gathers members from leading manufacturers,
national government agencies, PLM vendors and research organizations. PDES Inc. supports this
standard as an industry resource to sustain the interoperability of digital product information, ensuring
and maintaining authentic longevity throughout their product lifecycle.
Readers of this standard should note that all standards undergo periodic revisions and that any
reference made herein to any other standard implies its latest edition, unless otherwise stated.
The Standards will be published under two different standards organizations using different prefixes.
ASD-STAN will publish the standard under the number EN 9300–xxx. AIA will publish the standard
under the number NAS 9300–xxx. The content in the EN 9300 and NAS 9300 documents will be the
same. The differences will be noted in the reference documentation (i.e. for EN 9300 geometric
dimensioning & tolerancing will be referenced in ISO 1101 and ISO 16792, and for NAS 9300 the same
information will be referenced in ASME Y14.5M and Y 14.41). The document formatting etc., will follow
that of the respective editorial rules of ASD-STAN and AIA.
1 Scope
1.1 Introduction
This document defines the requirements on a digital archive to preserve for the long term the 3D
explicit geometry of single CAD parts. The goal is to preserve the 3D information without loss with
respect to the geometry produced by the original CAD system, following the principles laid down in
EN 9300-003 “Fundamentals and Concepts”, including the use of an open data format.
1.2 In scope
The following is in scope of this part of EN 9300:
— business specification for long term archiving and retrieval of CAD 3D explicit geometry
(see Clause 5);
— essential information of CAD 3D explicit geometry (solids, curves, surfaces, and points) to be
preserved (see Clause 6);
— data structures detailing the main fundamentals and concepts of CAD 3D explicit geometry
(see Clause 7);
— verification rules to check CAD 3D explicit geometry for consistency and data quality (see Clause 8);
— validation rules to be stored with the CAD 3D explicit geometry in the archive to check essential
characteristics after retrieval (see Clause 9).
NOTE This includes the geometrical external shape resulting from CAD disciplines 3D entities (e.g., 3D
Structural components, 3D Tubing, 3D electrical harness, 3D composite, etc.).
1.3 Out of scope
The following is outside the scope of this part of EN 9300:
— the formal definition of validation and verification rules to check 3D explicit geometry for
consistency and data quality using a machine-readable syntax;
— implicit or parametric geometry;
— Geometric Dimensioning & Tolerancing (GD&T), Product & Manufacturing Information (PMI);
— assembly structures;
— presentation of explicit geometry.
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.
EN 9300 (all parts), Aerospace series — LOTAR — LOng Term Archiving and Retrieval of digital technical
product documentation such as 3D, CAD and PDM data
ISO 1101:2012, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of
form, orientation, location and run-out
ISO 2768-1:1989, General tolerances — Part 1: Tolerances for linear and angular dimensions without
individual tolerance indications (First Edition)
ISO 2768-2:1989, General tolerances — Part 2: Geometrical tolerances for features without individual
tolerance indications (First Edition)
ISO 10303-42:2003, Industrial automation systems and integration — Product data representation and
exchange — Part 42: Integrated generic resource: Geometric and topological representation
ISO 10303-59:2014, Industrial automation systems and integration — Product data representation and
exchange — Part 59: Integrated generic resource — Quality of product shape data
ISO 10303-203:2011, Industrial automation systems and integration — Product data representation and
exchange — Part 203: Application protocol: Configuration controlled 3D design of mechanical parts and
assemblies
ISO 10303-214:2010, Industrial automation systems and integration — Product data representation and
exchange — Part 214: Application protocol: Core data for automotive mechanical design processes
ISO 10303-242:2014, Industrial automation systems and integration — Product data representation and
exchange — Part 242: Application protocol: Managed model-based 3D engineering
ISO 10303-514:1999, Industrial automation systems and integration — Product data representation and
exchange — Part 514: Application interpreted construct: Advanced boundary representation
ISO 16792:2006, Technical product documentation — Digital product definition data practices
ASME Y14.5:2009, Dimensioning and Tolerancing
ASME Y14-41:2012, Digital Product Definition Data Practices
FAA Part 21, Certification for Products, Parts & PMA
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 9300-007 and EN 9300-100
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Applicability
Refer to applicability of EN 9300-001, Clause 4.
5 Business specifications for the long term archiving and retrieval of CAD
mechanical 3D explicit geometry information
5.1 Introduction
General specifications for long term archiving of CAD mechanical design information are described in
EN 9300-100, in the clause “Fundamentals and concepts for long term archiving of CAD 3D mechanical
information”.
According to the clause “5.1 Different generations of CAD systems and associated methods of design”,
there are several methods of design:
— The first generation of CAD design method allowed the engineer to digitally create a 2D drawing
(without a 3D model). The essential information as well as the regulatory authority of the design
intent is represented by the 2D drawing.
— The second generation of CAD design method is based primarily on the use of 3D models with the
output being both 2D representation (drawings) and a 3D CAD dataset to drive CAM/CAI. The
regulatory authority of the design intent is represented by the 2D drawing.
— The third generation of CAD design method is based on the use of parametric and relational design.
The essential information as well as the regulatory authority of the design intent is represented by
the 3D model.
Figure 1 — Illustration of the major generations of CAD systems
EN 9300-110 part specifies long term archiving for CAD mechanical 3D explicit geometry generated in
CAD systems of the second and third generation.
5.2 Description of use cases for retrieval of CAD mechanical 3D explicit geometry
Use cases for long term archiving and retrieval of CAD mechanical are used to verify that the
specifications meet the business requirements, to identify any gaps that occur over time, and to fix
them. This is illustrated in Figure 2, extracted from EN 9300-100 Figure 2: “Links between Use Cases,
essential information and EN 9300-1xx parts”.
Figure 2 — Links between use cases, essential information and EN 9300-1xx parts
This clause sums up general requirements common to the aerospace industries, for the preservation of
the 3D external shape of the product. These requirements should be reviewed and adapted by each
company, according to its products and its business practices.
After retrieval from the long term archiving system, the CAD 3D information may be not exactly the
same as the original. This may result, for example, from the changes in mathematical representation of
the CAD modeller (“change of generation of CAD systems”), or from the evolution of their internal data
models through successive versions. The objective is to demonstrate that the process still preserves the
essential information for the 3D shape of the product, as defined by the original CAD system the
moment that the CAD information was released.
The type of CAD representation to be preserved differ according to the use cases (see EN 9300-100
Figure 4: Links between use cases, essential information and EN 9300-1xx parts). In the same way, the
tolerance thresholds for the verification rules and geometric validation properties are related to the
different use cases and to the specific requirements of each company. Such thresholds will not be
normatively defined in this standard, but values will be proposed in associated recommended practices.
Such tolerances depend on the precision of the CAD modeller; it is assumed that the precisions of the
modellers will increase overtime. They are also related to the categories of parts and to their functions.
As mentioned in the EN 9300-002, there are 4 main use cases for long-term archiving and retrieval of
CAD 3D exact geometry, and its complementary 2D drawings:
— documentation of aerospace & defence product design for regulatory and contractual compliance;
— aerospace & defence industry incident investigation (product liability);
— design re-use – product modification;
— product lifecycle support and disposal.
These use cases are detailed in the context of long term preservation of CAD mechanical 3D explicit
geometry information.
For more information, see Annex A.
5.3 Description of file content
— Scenario 1: part file with exact geometry only;
— Scenario 2: part file with tessellated geometry only;
— Scenario 3: part file with exact and tessellated geometry;
— Scenario 4: part file containing an assembly mixing exact and tessellated geometry (example:
Equipment internal geometry, see EN 9300-115 and EN 9300-125).
6 Essential information of explicit geometry
Essential information of 3D explicit geometry, captured in archive files, is defined as:
— the exact boundary representation shape of a single part within free tolerances of manufacturing
(e.g. according to ISO 2768 general tolerances);
— the tessellated boundary representation shape;
— the exact representation of curves;
— the tessellated representation of curves;
— the exact representation of surfaces;
— the tessellated representation of surfaces;
— the representation of points.
The EN 9300 standards shall be applied to any additional information not covered by this standard.
7 Definition of core model for an explicit geometry
To preserve the essential information of explicit 3D geometry the shape should be represented at
nominal size precisely and completely within the defined tolerances independent of tool specific
generation functions for geometry. Therefore a boundary representation as an accumulative topological
and geometric volume model has been chosen as core model for this part of EN 9300.
This core model is defined by ISO 10303-514 (advanced boundary representation) and ISO 10303-42
(geometric and topological representation). This representation is used by ISO 10303-203
(configuration controlled 3D design of mechanical parts and assemblies) CC08, ISO 10303-214 (core
data for automotive mechanical design processes) CC02 and ISO 10303-242 (managed model based 3D
Engineering). Therefore STEP physical files meeting ISO 10303-203 CC08 or ISO 10303-214 CC02 or
ISO 10303-242 may be used for the ingest of explicit geometry. The descriptive information of the AIP
shall document the versions of both EN 9300-110 and ISO 10303 application protocol that are basis for
the AIP .
Other geometric information or information related to geometry such as design history, layer
information, auxiliary geometry or technical attributes like roughness or tolerances as modelled in
typical CAD systems may be maintained together with the 3D explicit geometry within the same STEP
file, assuming that this information can be represented by the chosen application protocol of ISO 10303.
In this case additional validation properties and verification rules defined in the respective parts of
EN 9300 should be applied to ensure the preservation of this additional information.
8 Verification rules of explicit geometry
8.1 Introduction
As described in “Authentication and Verification” (EN 9300-005), verification is one of the two basic
qualification methods to reduce the risk of losing essential information during long term archiving.
The verification of the source and the target CAD model are not required in this standard, but the
quality of the exported file in the archival format is strongly dependant of the quality of the source CAD
model, and lack of verification creates a risk that the retrieval process will fail.
The verification for 3D explicit geometry described in this clause concerns only the archival file during
the ingest process (EN 9300-012).
To improve the longevity of the archive, companies may decide to add new verification rules and to
check a selection of the archived files. In this case, the company may decide to archive the new
verification report, and according to the result, to carry out the appropriate action to ensure the long
term preservation of the CAD archived information.
If a verification of the native target CAD model is implemented in the retrieval process (EN 9300-014),
the CAD model shall pass the validation process before the model will be fully acceptable. Verification
process is required to minimize the risk of data loss or unacceptable change between archival and
retrieval. This process shall be applied to the STEP file during archival ingestion, to the STEP file after any
archival preservation conversion. It is strongly recommended that this process is also applied to the target
CAD model after STEP import.
AIP: Archive Information Package. (see part EN 9300-007 “Terms and definitions”).
8.2 Level of verification
Conversion of CAD models between different formats may lead to the loss of geometrical and
topological elements.
To minimize the risk of such kind of problems, companies shall choose one of the following three levels
of verification:
— verification level 0, no verification, which entails accepting the maximum risk of failure at retrieval;
— verification level 1, with an controlled risk, and using list of verification rules defined below;
— verification level 2, with a minimum risk by the use of verification level 1 rules, plus additional
verification rules defined by the company.
For exact solid and surface, the rules for the verification level 1 are a subset of the rules defined in the
SASIG PDQ, ISO 10303-59, which provides a definition for each rule, an illustration of the defects
detected by the rule, and, where possible, a method to fix the defects.
For tessellated solid and surface, the verification rule level 1 can consist of a check such as a watertight
tessellation.
For verification level 2, companies may check using their own verification rules, see Annex D
(informative) – Recommended verification rules level 1 and level 2.
For example 1, multiple identical elements (points, curves, surfaces) can be problematic for some
business case, and the distance between two identical elements need to be within a given tolerance that
may change from one system to another system (e.g., change of generation of CAD modellers).
For example 2, specific rules for the verification of the structure of the CAD model (colour and layers)
may be added.
Some rules are parameterised by acceptance thresholds. For the long term retention of 3D explicit
geometry, the verification level 1 shall be applied with appropriate thresholds in the ingest process. For
the retrieval process, this is not required.
8.3 Geometrical verification rules and appropriate thresholds
8.3.1 Verification rules
Verification is applied to the B-REP-STEP-file according to of ISO 10303-514 and ISO 10303-42.
The verification rules level 1 shall be applied by each company. These are required to ensure a high rate
of success for the import process of the archival file, and for retrieval of the shape of the parts without
significant change.
The method used to define the verification rules (both level 1 and level 2), and the initial set of the
recommended verification rules for level 1 can be found in the Annex D.
The set of verification rules may change over the time following successive upgrades of the CAD
systems. To add new verification rules, the method in Annex D should be used.
Two ways to verify the quality of the STEP files have been identified:
— using a STEP checker which includes its own geometry kernel;
— using a CAD checker after import of the STEP file into a CAD system.
If a checker does not implement the verification rules level 1, a mapping with its own verification rules
shall be documented and a qualification provided with appropriate test cases.
Following the change of CAD system and its STEP interfaces, the list of verification rules may be adapted
using an adequate method, as described in Annex D. Otherwise the list of verification rules level 1
should be applied.
A company may remove a verification rule from level 1 if it is demonstrated and documented that the
users' methods or the operational CAD system does not allow the quality defects detected by the rule to
occur in STEP files.
Before implementing the ingest processes, it is recommended that an analysis takes place of the CAD
system interfaces export options and their consequences for the contents of STEP files. For example, an
option to export or not the entities placed in a no show mode may have an impact on verification.
8.3.2 Evaluation of the values of thresholds
Verification may be done by checkers, which shall be compliant with the rules for the verification level 1
and level 2.
Following the precision of the parts, the quality of the computation, and the precision of the source CAD
systems, a threshold per types of CAD parts and per rule may be defined.
NOTE As a result, the thresholds for each verification rule cannot be standardized. The thresholds in Annex D
are informative.
If required for particular rules and categories of CAD parts, a second threshold may be defined to
indicate a “warning” rather than a failure.
The example below shows that for the same rule, the “Edge Gap” thresholds are significant for import
success:
— When there are only negligible gaps between connected edges in a STEP model, receiving CAD
systems are able to import the geometry with negligible shape changes, including maintaining the
BREP solid definition, see Figure 3 “No_Edge_Gap”.
— When the gap between connected edges is too large in the STEP model, it is usually too difficult for
the receiving CAD system to close it sufficiently to create a solid model. In this case, the model on the
right was imported as an open shell, see Figure 4: “Unacceptable_Edge_Gap”.
Figure 3 — No Edge Gap
Figure 4 — Unacceptable Edge Gap
This implies that the checker should be qualified against the verification rules and thresholds, and all
changes in this tool shall be approved. This qualification shall include test cases with known defects
after import of the archival files into different geometry kernels. The method for qualification is out of
the scope of this standard. A qualification of the STEP file checker by Export and Import in the same
CAD system is not enough because the same error may occur consistently.
Verification is considered as successful if all the results of the rules are within the appropriate
thresholds.
Verification is considered as unsuccessful if any one of the results is outside the appropriate thresholds.
If the verification process identifies errors or fails to provide results, the ingest process shall be stopped
and an error handling process shall notify the administrator of the archive system. The producer should
be also informed.
8.4 Results of the verification
Verification shall provide the following results:
— a status information;
— a verification report (text format), including for each defect the highest overall values and the
required thresholds;
— optionally, a graphic report to identify the defects detected on the shape.
It is recommended that status information be stored and used for statistical purposes. In every case, the
producer shall be informed of the results of the verification.
8.4.1 Status information
Three classes of status information are distinguished:
— passed;
— failed;
— not performed.
“Passed”means that the CAD model could be ingested in the archival system.
“Failed” means that the CAD model is rejected, and that the defects should be corrected before
resubmitting.
“Not performed” means that no result was created by the verification process.
A company may define a derogation process to accept an original model including defects (for example
where the manufactured part is in service and has no problems), in which case a status “Derogated”
shall be applied. This information shall be provided to the consumer on retrieval, in order to manage
these defects.
8.4.2 Verification reports
The verification report containing the result of each rule shall be created and stored in the Archival
Information Packages (AIP). In cases of failure in the verification, an error report is sent to the provider
to inform them of the failure.
These verification reports shall contain the following mandatory information:
— the creation date of the file;
— the name of the checked STEP file;
— the values for each rules of verification level 1 and corresponding thresholds.
These verification reports may also contain also the following information:
— results of additional rules;
— status information.
If needed, this report may be sent to the producer for information.
9 Validation rules of an explicit geometry
9.1 Introduction
As introduced in the part “Authentification and Verification” (EN 9300-005), validation is one of the two
basic qualification methods to reduce the risk of losing essential information during long term
archiving.
For the 3D explicit geometry, the main essential information is the shape. The source CAD model must
contain at least one exact or tessellated solid/surface/curve/point (the verification of the source CAD
model is not required in this standard).
Validation for 3D explicit geometry is an end-to-end process including:
— In the ingest process (EN 9300-012) validation properties are computed, stored in the archive
format either defined in neutral format such as STEP, or in a specific validation property file in an
open format stored in the Archival Information Package (AIP). If the computation failed, an error
report is sent to the provider to inform them of the failure.
— In the retrieval process (EN 9300-014) the validation properties are recomputed and compared
with the original validation properties and a status file is created with the result passed, failed or
not performed.
The computation of the Geometrical Validation Property (GVP) may be done by the CAD system or by
the STEP converter or by a stand-alone batch application.
An information status is required to continue the retrieval process. For example, if this comparison is
outside of the threshold (status failed), the verification of the target CAD file could be optional.
NOTE After a failed validation the retrieved file may be provided to the consumer with a validation report. If
the consumer refuses the CAD model, a healing process may be done, and the result reassessed using the same
validation process.
9.2 Level of validation
Conversion of CAD models between different formats may lead to the loss of topological elements.
To minimize the risk of such problems, companies shall choose one of the following three levels of
validation:
— validation level 0, no validation, with maximum risk;
— validation level 1, the use of global validation properties, which has an intermediate risk
(see Table 1 — Validation properties level 1).
Table 1 — Validation properties level 1
Validation level Validation level 1
Exact solid Volume, Centre of Gravity, Area
Exact independent surface/open shell Centre of Gravity, and Area
Independent Curve Length
Exact independent curve
Independent Curve Centroid
Tessellated solid Surface area, centroid
Tessellated surface Surface area, centroid
Tessellated curve Total length, centroid

— Validation level 2 where risk is minimised by the use of validation properties in addition to level 1,
such as the “Cloud of Points validation properties, or additional validation properties defined by the
company.
— Number of facets and segments have a potential to change so counting them could be problematic
due to their potential to change. This validation can be applied at a Company’s discretion.
For exact solids, surfaces and curves, the validation properties volume, centre of gravity, area and cloud
of points are described in the recommended practices “geometrical validation properties”(see the CAD
implementer forum web site: http://www.cax-if.org/).
For tessellated solids, surfaces and curves, the validation properties are described in the recommended
practices for 3D tessellated geometry.
For the long term retention of 3D explicit geometry, either validation level 1 or level 2 shall be applied
with appropriate threshold.
For the independent point, there is no validation properties defined for the level 1. Nevertheless,
company can define their own validation properties according their use cases.
9.3 Comparison of the Geometrical Validation Properties (GVP)
The comparison between GVP is a function of the precision of the parts, of the quality of the
computation, and of the precision of the source and target CAD systems. This is means that for each GVP
several thresholds may be defined.
If required for a particular GVP and particular categories of CAD parts, a second threshold could be
defined to provide “warning” information.
For example, for the volume GVP, the threshold will be larger where two different GVP algorithms are
used - say the native algorithms of the source and target CAD systems - and smaller where the same tool
calculates the property at ingest and retrieval.
A qualification of the algorithms used for the computation of GVP in the ingest and the retrieval process
is required to define the values of the thresholds, even if specifics tools are used. The aerospace
company shall define the appropriate thresholds according to its specific categories of products. This is
also valid for additional GVP chosen by companies.
This qualification may be done using test cases for the GVP calculated in different geometry kernels, but
such a method is out of the scope of this standard.
For qualification of a GVP algorithm, import and export using the same source CAD system is not
adequate, since the CAD system may make the same error consistently.
Each company shall document the algorithm of comparison used in its internal process.
The conversion of explicit geometry is successfully validated if all the results of GVP comparisons are
lower than the thresholds.
The conversion of the explicit geometry fails if one of the results of GVP comparisons is higher than its
threshold.
NOTE For the GVP cloud of point, the threshold is the maximum deviation authorized between sampling
points computed from the source CAD model, and their projections onto the shape of the target CAD model.
All changes in the GVP computation tools shall be documented and tested with test cases, according the
requirement described in clause 8 “Preservation planning of archived CAD information” of Part
EN 9300-100 “Common concepts for Long term archiving and retrieval of CAD 3D mechanical
information”.
9.4 Results of the validation
9.4.1 At the ingest process (qualify)
If creation of the values of the GVP fails, an error report is sent to the provider to inform them of the
failure. In this case the ingest process is stopped and no validation report is made.
After the computation of the GVPs, a validation report shall be created and stored in the Archival
Information Packages (AIP), and the values of GVPs shall be stored in the AIP.
These “qualified” validation reports shall contain the following mandatory information:
— the creation date of the file;
— the name of the source CAD model;
— the name of the file containing the validation properties in an AIP;
— the versions of all applications involved in the computation of the GVP in the ingest process.
These “qualified” validation reports can contain also the following information:
— the values for all GVP level 1;
— other additional validation properties.
If needed, this report could be sent to the consumer for information.
9.4.2 At the retrieval process (comparison)
The comparison of the GVP shall provide the following results:
— a status information;
— a validation report (text format) for the consumer including the GVPs computed in the ingest
process, the GVPs computed in the retrieval process, the results of the comparison, and the
thresholds;
— optionally, a graphic report to show the change to the shape (this functionality is available with the
cloud of points, by identifying all faces where deviation of sampling points are outside the
threshold).
It is recommended that all status information be stored and used for statistical analysis.
The consumer shall be informed of the results of the validation.
9.4.2.1 Status information
Three classes of status have to be distinguished:
— passed;
— failed;
— not performed.
Passed implies that the retrieved CAD model may be provided to the consumer.
Failed implies that the retrieved CAD model may be also provided to the consumer, but with the
validation report highlighting the failure. Depending on the defects, the consumer accepts or rejects the
CAD model.
Not performed means that the conversion in the target CAD system has failed and the comparison
process could not be done. In this case, any CAD model may be provided to the consumer, and an error
report is sent to the administrator of the archive system. After a repair process, a new validation shall to
be done to create a validation report with the same validation process.
9.4.3 Validation reports
These validation reports shall contain the following mandatory information:
— the creation date of the file;
— the name of the target CAD model;
— the versions of all applications involved in the calculation of the retrieval process.
These validation reports shall contain at least one of the following information:
— status information;
— a comparison between the source and target GVPs.
(informative)
Description of use cases for long term archiving and retrieval of CAD 3D
explicit geometry
As presented in 5.2, this Annex is informative. It aims at providing the recommended approach to
describe the business context and tasks to ensure, according to the four main use cases for long-term
archiving and retrieval of CAD 3D explicit geometry, and the complementary 2D drawings:
— documentation of aerospace & defence product design for regulatory and contractual compliance;
— aerospace & defence industry incident investigation (product liability);
— design re-use – product modification;
— product lifecycle support and disposal.
A.1 Documentation of aerospace & defence product design for regulatory and
contractual compliance
Use case summary
Aerospace manufactures and defence contractors are required to retain the design data that describes
their products as long as the product is in service. For commercial airplane manufacturers, this is based
on regulatory requirements. For defence contractors this is typically a contractual requirement.
Alternatively, the contract may require that the contractor hand over the design data to their customers
but continue maintain it.
Organizations involved
The aerospace/defence contractor’s engineering organization is typically the producer of the product
design definition and their engineering function is typically responsible as the data owner. For the
commercial aerospace environment, the regulatory or certification agency is the consumer. For the
defence/space environment, defence ministries, space agencies, or some other government agency
would be the consumer. The manufacturer (and the defence contractor if contractually obligated) has
the responsibility to maintain the product design definition and must also manage and administer the
repository of retained data.
Purpose of use case
Commercial airplane and engine manufacturers are required to retain type design data in order to
document the type design of the airplane/engine. Certification agencies, such as the FAA or EASA, issue
type certificates based on the type design. The type design must be available on request from the
certification agency for the duration of the product life.
The aerospace & defence industry must often also ensure that the product design definition is available
on request by the owning agency for the duration of the product life. The product life may vary from
very short terms to several decades.
Historical process if applicable
The method used by many contractors is to create the design of an aerospace product using a 3D CAD
system. The 3D model is then used to create the 2D drawings. Each part is completely defined by 2D
drawings, which define dimensions, tolerances and other annotations. To archive the state of
manufacturing, the 2D drawings are converted to an image format, such as a raster
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