Why does Writer offer two options for saving in DOCX format?

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Does the 2nd option mean FULL compliance with ISO/IEC 29500 Strict, as MS Office 2007/2010 is known to be non-compliant with this standard?

According to the answer given by a developer here, and in simple terms, the answer is yes. The "Microsoft Word 2007/2010/2013 XML (.docx)" entry has (under LO v4.2) had "2013" added to the "2007/2010" indicating that this is ISO/IEC 29500 Transitional. MS Office 2013 does not write out ISO/IEC 29500 Strict by default (it has to be manually selected). The "Office Open XML Text (.docx)" option is targeting ISO/IEC 29500 Strict, but support is not yet "full."

The complete story of which versions of MS Office support which versions of the various formats developed by Microsoft is a bit of a tangle. There is an excellent article Complex singularity versus openness by Markus Feilner over in the European Commission e-Library. It indicates how the three different forms of Office Open XML (OOXML)[1] have created a nightmare situation for organsations and individuals alike. It is virtually impossible to talk about "DOCX" as a format due to the varying degree of support across different versions of MS Office.

Ultimately the only form of OOXML that matters is ISO/IEC 29500 Strict but it will be some time before: a) LO fully supports this standard; b) Microsoft Office writes this file format out as the default. Until (b) happens it is unlikely TDF/LO will advocate using the "Office Open XML Text (.docx)" entry in the pull down list.

[1] A basic indication is provided in the answer here.

EDIT: This answer contains several inaccuracies. I (@oweng) have tried to edit it, but the site keeps dying, so I have posted a separate answer.

Sorry the answer to the ASKED question.

Why [does] Writer offer TWO option of saving document in DOCS format?

1. Microsoft 2007/2010 docx
2. Office Open XML docs

From wikipedia

1) Microsoft 2007/2010 docx

The Microsoft Office XML formats are XML-based document formats (or XML schemas) introduced in versions of Microsoft Office prior to Office 2007. Microsoft Office XP introduced a new XML format for storing Excel spreadsheets and Office 2003 added an XML-based format for Word documents.[1]

These formats were succeeded by Office Open XML (ECMA-376) in Microsoft Office 2007.

2) Open Office XML docs

Office Open XML (also informally known as OOXML or OpenXML) is a zipped, XML-based file format developed by Microsoft[2] for representing spreadsheets, charts, presentations and word processing documents. The Office Open XML specification was initially standardised by Ecma (as ECMA-376) and later by ISO and IEC (as ISO/IEC 29500).

Starting with Microsoft Office 2007, the Office Open XML file formats have become the default[3] target file format of Microsoft Office.[4][5]

Does it mean that 2nd option means FULL compliance
with ISO/IEC 29500:2008/ECMA-376 2nd edition (2008),
as MSO 2007/2010 is, as known, not fully compatible
with these standards?

Good question! @Khawar Nehal might have more info on this point. Per what he discovered on Wikipedia:

Microsoft Office 2010 provides read support for ECMA-376, read/write support for ISO/IEC 29500 Transitional, and read support for ISO/IEC 29500 Strict.[6] Microsoft Office 2013 additionally supports both reading and writing of ISO/IEC 29500 Strict.[7]

I'm not sure what that means for LO's support of this format.

Regards,
Khawar Nehal
http://dubai-computer-services.com

and

@qubit

There are multiple DOC formats.

There was MS Word 1.0, 2.0 6.0 (No 3,4,5 because of wordperfect jealousy) then 95, 97,2000,2003,2007,2010 and now 2013. There are minor changes which MS makes to the formats.

LibreOffice allows saving to these formats to facilitate the receiver to get the one which closely matches their opening software.

If in doubt, save as DOC and not DOCX. Select the simplest Word 6.0 for max compatibility with most DOC opening softwares.

For max layout you need the max DOC format that is 97/2000/2003 DOC then for more compatibility use DOCX

More than that you need MS Office. You can use the web based version.

If you still have formatting issues, then you need to make sure all printer settings are ok.

Beyond that, you can ask the user to get libreoffice and send a odt.

More than that you need to use a PDF.

If you still need more than send a JPEG and hope the receiver knows how to print that in a reasonable size. Good luck.

Regards,

Khawar Nehal http://dubai-computer-services.com

Never work in or save as .docx.

Have you switched off the LO warning that data and formatting may be lost if you save as any format except .odt? Switch it back on in Tools > Options ...

Still no answer to this simple question? If someone at the Libreoffice team adds these two possibilities in the menu, he (or she) must know why I suppose?

According to Microsoft, docx is a newer format and better than odt. They suggest that Libreoffice should also migrate to docx as standard format.