Another ZIP issue -- Does OPC allow use of split/segmented ZIP file?

[Francis Cave]

Caroline, Murata-san

 

I think we’re going to need to carefully review Part 1 §9 Packages, in particular to make sure that any changes in terminology that we wish to make in Part 2 are consistent with Part 1 (e.g. “ZIP archive”).

 

I’m particularly interested in what §9.1.5 has to say about Trash Items. This implies that a package can contain items that are not Parts, because they don’t have associated content types and they are not the targets of relationships. 

 

Kind regards,

 

Francis

 

 

 

From: caroline arms <caroline.arms at gmail.com> 
Sent: 11 May 2018 11:50
To: Makoto Murata <eb2m-mrt at asahi-net.or.jp>
Cc: SC34 <e-SC34-WG4 at ecma-international.org>
Subject: Another ZIP issue -- Does OPC allow use of split/segmented ZIP file?

 

Murata-san,

Here is another issue that probably needs to be run by Microsoft experts.


>From APPNOTE 6.2.0  -- https://www.pkware.com/documents/APPNOTE/APPNOTE-6.2.0.txt

"Large .ZIP files can span multiple diskette media or be split into user-defined segment sizes." 


However, APPNOTE 6.2.0 does not seem to explain how splitting into user-defined segment sizes is done.


Part 2 Annex B appears to disallow "multi-disk archives" in Table B-1

Part 2 does not seem to mention segments or splitting in the context of ZIP

 

Part 1 does not seem to say anything about segments in the context of ZIP

 

I suspect that we should explicitly disallow splitting into user-defined segment sizes.  

 

Further exploration reveals:


APPNOTE 6.3.3  -- https://www.pkware.com/documents/APPNOTE/APPNOTE-6.3.3.TXT
-- which is what ISO/IEC 21320-1 is based on, does explain the splitting/segmenting technique, in clause 8.  There is no equivalent text in APPNOTE 6.2.0 

 

ISO/IEC 21320-1 explicitly disallows both spanning multiple volumes and splitting into user-defined segments

Also possibly relevant:

>From APPNOTE 6.2.0
"5)  Spanned/Split archives created using PKZIP for Windows
          (V2.50 or greater), PKZIP Command Line (V2.50 or greater),
          or PKZIP Explorer will include a special spanning 
          signature as the first 4 bytes of the first segment of
          the archive.  This signature (0x08074b50) will be 
          followed immediately by the local header signature for
          the first file in the archive.  A special spanning
          marker may also appear in spanned/split archives if the
          spanning or splitting process starts but only requires
          one segment.  In this case the 0x08074b50 signature
          will be replaced with the temporary spanning marker
          signature of 0x30304b50.  Spanned/split archives
          created with this special signature are compatible with
          all versions of PKZIP from PKWARE.  Split archives can
          only be uncompressed by other versions of PKZIP that
          know how to create a split archive."

Part 2 Annex B does mention    0x08074b50  in B.3

I was thinking that if you were forwarding a question on unknown parts to Microsoft now, you might send one on this issue too.

      Caroline

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