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<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi all – for reference, here are the definitions of “logical item name” (which really seems to me to actually define “logical item”), “piece” and
“zip item” from the T&Ds:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><b><span style="font-size:11.0pt;font-family:"Calibri,Bold","sans-serif"">logical item name
</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">— An abstraction that allows package implementers to manipulate physical data items<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">consistently regardless of whether those data items can be mapped to parts or not or whether the package is<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">laid out with simple ordering or interleaved ordering.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><b><span style="font-size:11.0pt;font-family:"Calibri,Bold","sans-serif"">piece
</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">— A portion of a part. Pieces of different parts can be interleaved together. The individual pieces are<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">named using a unique mapping from the part name. Piece name grammar is not equivalent to the part name<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">grammar. Pieces are not addressable in the package model.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><b><span style="font-size:11.0pt;font-family:"Calibri,Bold","sans-serif"">ZIP item
</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">— A ZIP item is an atomic set of data in a ZIP archive that becomes a file when the archive is<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">uncompressed. When a user unzips a ZIP-based package, the user sees an organized set of files and folders.</span><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m not sure what you mean about the relationship being 1:1 – a piece, for example, definitely does not always correspond to a whole part. But
I might be misunderstanding your wording. Here’s my take on these terms though:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The term “ZIP item” is used only when talking about the ZIP structure and 10.2 makes clear that once the ZIP item is out of the ZIP it’s just a
Part [unless interleaving was involved, in which case it’s a set of pieces which will become a Part, as per 10.1.4].<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">“Piece” is, I think, defined quite clearly in 10.1.4 which describes interleaving and the part of the piece (ahem).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I think that a logical item is what you have when you take a complete physical package item, after applying any interleaving if necessary.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m slightly less clear on physical package items and how exactly they relate to ZIP items or logical items. There’s a section in 10.1.3 concerning
that which is quite verbose but I’m still slightly unsure of the purpose of logical items (when not used simply to put back together interleaved segments).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m not sure whether a ZIP item
<i>is</i> a physical package item, or is in fact a further stage on top of that.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This is probably a good topic to dig into in Prague – John’s on vacation until just before we leave, but I’ll try to sit down with him before the
meetings to see what his thoughts are on this.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Chris<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> eb2mmrt@gmail.com [mailto:eb2mmrt@gmail.com]
<b>On Behalf Of </b>MURATA Makoto<br>
<b>Sent:</b> 04 June 2014 00:18<br>
<b>To:</b> SC34<br>
<b>Subject:</b> Item and piece in OPC<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Dear colleagues,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">There are four similar (if not identical) terms in OPC. They are<o:p></o:p></p>
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<p class="MsoNormal"> 1) logical item<o:p></o:p></p>
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<p class="MsoNormal"> 2) physical package item<o:p></o:p></p>
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<p class="MsoNormal"> 3) ZIP item, and<o:p></o:p></p>
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<p class="MsoNormal"> 4) piece<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The relationship between any two of them is 1:1.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Then, how are they different from each other? Here <o:p></o:p></p>
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<p class="MsoNormal">is my understanding.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">- "Logical item" is independent from <o:p></o:p></p>
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<p class="MsoNormal"> the underlying physical representation<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">- "ZIP item" is dependent on the ZIP format<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">- "physical package item" is either "ZIP item"<o:p></o:p></p>
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<p class="MsoNormal"> or XXX item, where XXX is a particular <o:p></o:p></p>
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<p class="MsoNormal"> physical representation<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">- "piece" is used only when interleaving is involved.<o:p></o:p></p>
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<p class="MsoNormal"> It is not clear whether "piece" is a logical item, <o:p></o:p></p>
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<p class="MsoNormal"> ZIP item, or physical package item.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Regards,<o:p></o:p></p>
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<p class="MsoNormal">Makoto <o:p></o:p></p>
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