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0027069Community[OCCT] OCCT:Data Exchangepublic2016-01-09 21:332020-09-11 18:46
Roman Lygin 
[OCCT] 6.9.1 
[OCCT] 7.6.0* 
bugs xde bug27069
0027069: IGES parser does not recognize comments in Parameters section
The IGES parser is not able to recognize comments which are allowed by the IGES spec, issues false positive warnings, and populates IGES model with invalid data. As a result the IGES file cannot be converted afterwards.

This is a root-cause of issues reported at See also attached a simpler reproducer.

Excerpt from IGES spec 5.3:
" Any desired comment may be added after the record delimiter. Additional comment lines may be used by keeping the same Directory Entry pointer in Columns 65-72 and including the comment lines in the entity’s parameter line count (DE Field 14)."
igesbrep points-with-comments.igs
data c
# must be no warnings/errors
Preliminary analysis shows that the IGES parser does not attempt to associate P section entries to D section entities using references from D to P. Instead it uses a consecutive list of parameters from the P section and just incrementally associates them to D entities. When the parser encounters a multi-line comment or a comment taking a new line in the P section it mistakenly interprets it as a string parameter what breaks this incremental association and thus further parsing.

No fix currently available.
No tags attached.
? points-with-comments.igs (1,394) 2016-01-09 21:33
Issue History
2016-01-09 21:33Roman LyginNew Issue
2016-01-09 21:33Roman LyginAssigned To => gka
2016-01-09 21:33Roman LyginFile Added: points-with-comments.igs
2016-10-26 11:54gkaTarget Version7.1.0 => 7.2.0
2017-07-27 09:24abvTarget Version7.2.0 => 7.4.0
2017-08-17 14:36mkvTest case number => bugs xde bug27069
2017-08-17 14:36mkvNote Added: 0069523
2019-09-04 13:04abvTarget Version7.4.0 => 7.5.0
2020-09-11 18:46gkaTarget Version7.5.0 => 7.6.0*

2017-08-17 14:36   
Problem described in issue is reproduced on current state of OCCT.