Hello trid users,
some days ago i run TrID on riff based Corel examples with name extension
cmx. Such files are identified correctly by cmx.trid.xml as "Corel Metafile
Exchange Image (Legacy)" ( see appended output/trid-old.txt).
According to reference URL it is possible to distinguish between version
"Presentation Exchange 5.0" and "Presentation Exchange 6+" by PRONOM
"x-fmt/34" or "x-fmt/35".
So i run DROID (Digital Record and Object Identification) on CMX files.
This 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 CMX files inside directory cmx-v5 are described here as "Corel
Presentation Exchange File" with version 5.0. ( see appended
cmx-v5/output/DROID-cmx-v5.csv).
The other CMX files are described as "Corel Presentation Exchange File" with
version 6 and Later. ( see appended output/DROID-cmx-v6.csv).
So i run tridscan on version 6 samples and get definition file cmx-v6.trid.xml.
After deleting null patterns, approximating cmx.trid.xml and comparing with
DROID skeleton sample x-fmt-35-signature-id-731.cmx the resulting definition
has one additional byte pattern expressed by XML construct:
<Bytes>32</Bytes>
<ASCII> 2</ASCII>
<Pos>74</Pos>
So mention this fact by remark line:
<Rem>2 at position 74 indicates version 6 and later</Rem>
I am not sure, but this file format seems to be used til version 15. Since
version 16 then another file format is used.
And this version are now described by line:
<FileType>Corel Metafile Exchange Image (v6)</FileType>
Then i do the same procedure for version 5 samples to get cmx-v5.trid.xml
with 1 other byte pattern expressed by XML construct:
<Bytes>31</Bytes>
<ASCII> 1</ASCII>
<Pos>74</Pos>
With the new 2 definition files the Corel CMX samples are now described more
precisely ( see appended output/trid-new-v.txt and
cmx-v5/output/trid-new-v.txt). TrID definitions, some examples and output are
stored in archive cmx.zip. I hope that my 2 XML files can be used in future
version of triddefs as replacement for cmx.trid.xml.
With best wishes
Jörg Jenderek
