Hello trid users,
some days ago i run TrID on OLE2 Compound File based Bentley MicroStation CAD drawings. Most are
identified by dgn-microstation.trid.xml as "Bentley MicroStation CAD
drawing (alternate)". Some examples like CivilSeed.dgn are only described as
"Generic OLE2 / Multistream Compound File" by docfile.trid.xml
( see appended output/trid-old.txt).
The newest version of file command {
https://en.wikipedia.org/wiki/File_(command) } identifies such CAD
drawings as OLE 2 Compound Document and Microstation V8 CAD ( see
appended output/file-new.txt).
DROID (Digital Record and Object Identification) is a software tool
developed by The National Archives to perform automated batch
identification of file formats. See
https://digital-preservation.github.io/droid/ . The DGN files are here
described as "Bentley V8 DGN" by fmt/502. ( see appended
output/droid-dgn.csv).
So i changed describing text to "Bentley MicroStation CAD drawing
(v8)". Furthermore i replaced company URL
http://www.bentley.com/ by
URL about MicroStation on Wikipedia which is now expressed by line:
<RefURL>
https://en.wikipedia.org/wiki/MicroStation</RefURL>
When i run tridscan on undetected samples i get an updated trid
definition file. The UTF string DOCUMENT in global string section
vanished. Also one 0 and MICROSTATION string disappeared. The last is
not surprising, because name of creating application is "MicroStation"
in many cases, but also "Power GEOPAK" in examples like
city2DSubdivision.dgn gpk_xssheet_temp_file_4439726.DGN or "AECOsim
Building" in D-border.dgn is used. This is shown by internal cdf
subroutine of file command ( see appended output/file-cdf.txt).
With the updated definition file the undetected DGN samples are now
recognized, but besides DGN files also examples with DGNLIB and CEL
file name extension are described as MicroStation CAD drawing, but
apparently these two extension are used for MicroStation CAD drawing
library. So tried to look for differences between MicroStation library
and pure CAD drawings. Maybe string DGN~MIX only occurs in library, but
i not sure about this. So i generalize the definition file by adding
these two additional file name extensions. This is now expressed by line
<Ext>DGN/DGNLIB/CEL</Ext>
Now i also mention these differences by remark line like:
<Rem>DGNLIB and CEL extensions are used for library</Rem>
With the updated trid definition all CAD examples and libraries are
now described more precisely ( see appended output/trid-new-v.txt).
TrID definitions, some examples and output are stored in archive
dgn_.zip. I hope that my XML file can be used in future version of
triddefs.
With best wishes
Jörg Jenderek
