Office Open XML (frequently referred to as OOXML or, erroneously, as OpenXML) is an XML-based file format specification for electronic documents such as spreadsheets, charts, presentations and word processing documents.

Microsoft originally developed the specification as a successor to its binary Microsoft Office file formats and it was handed over to Ecma International to be developed by the Ecma International Technical Committee TC45, as the Ecma 376 standard, which was published in December 2006.

Controversially, the specification is currently undergoing fast-track standardization within ISO/IEC as DIS 29500 (Draft International Standard 29500), but the draft text did not get sufficient approval from ISO/IEC national body members to be approved as a full International Standard in a round of voting that took place in September 2007. A ballot resolution process will allow for the text to be amended, and a final decision will be reached on its approval at the end of March 2008.

Background

Prior to the 2007 edition of Microsoft Office, its component applications (such as Word and Excel) used binary file formats for storing data by default. Historically, these formats have been difficult for developers to work with natively, due to a lack of publicly available information on, and royalty-free access to, the format specifications, although Microsoft does offer a subset of these binary format specifications under a royalty free covenant not to sue. Despite these difficulties, a level of support has been achieved, though full interoperability has remained elusive. In 2000, Microsoft released an initial version of an XML based format for Excel, then in 2002 a new file format for MS Word followed. These formats were later incorporated into the 2003 release of Microsoft Office 2003, known as Office 2003 XML formats.

In 2004 governments and the European Union recommended to Microsoft that they publish and standardize their XML Office formats through a standardization organization. Microsoft decided in November 2005 to standardize the new version of their Microsoft Office XML format through Ecma (renamed as Ecma Office Open XML).

File format and structure

In the earlier form of these formats, prior to Ecma standardization, the Microsoft Office 2003 XML formats used a single monolithic file with embedded items like pictures as binary encoded blocks within the XML. Office Open XML no longer supports those but uses a file package conforming to the Open Packaging Convention. This format uses the ZIP file format and contains the individual files that form the basis of the document. In addition to Office markup, the package can also include embedded (binary) files in formats such as PNG, BMP, AVI or PDF.

Document markup languages

An Office Open XML file may contain several documents encoded in specialized markup languages corresponding to applications within the Microsoft Office product line. Office Open XML defines multiple vocabularies (using 27 namespaces and 89 schema modules.) The primary markup languages are WordprocessingML for Word-processing, SpreadsheetML for Spreadsheets, and PresentationML for presentations. DrawingML is used for vector drawing, charts, and for example, text art. Additionally, though deprecated, VML is supported for drawing.

Shared markup language materials include:

Office Math Markup Language (OMML)

Extended properties

Custom properties

Variant Types

Custom XML data properties

Bibliography

In addition to the above markup languages custom XML schemas can be used to extend Office Open XML.

The XML Schema of OOXML emphasizes reducing load time and improving parsing speed. In a test with applications current in April 2007, XML based office documents were slower to load than binary formats. For speed, OOXML uses very short element names for common elements and spreadsheets save dates as index numbers (starting from 1899 or from 1904). In order to be systematic and generic, OOXML typically uses separate child elements for data and metadata (element names ending in Pr for properties) instead of using multiple attributes, which allows structured properties. OOXML does not use mixed content but uses elements to put a series of text runs (element name r) into paragraphs (element name p). The result is terse and highly nested in contrast to HTML, for example, which is rather flat, designed for humans to write in text editors and is more congenial for humans to read.

OMML

Office Math Markup Language is a mathematical markup language that can be embedded in WordprocessingML, with intrinsic support for including word processing markup like revision markings , footnotes, comments, images and elaborate formatting and styles. The format is different from the World Wide Web Consortium (W3C) MathML recommendation, but is partially compatible through comparatively simple XSL Transformations.

DrawingMLExample of DrawingML text effects

DrawingML is the graphics markup language used in OOXML documents. Its major features are the graphics rendering of text elements, graphical vector based shape elements, graphical tables and charts.

The DrawingML table is the third table model in Office Open XML (next to the table models in WordprocessingML and SpreadsheetML) and is optimized for graphical effects and its main use is in presentations created with PresentationML markup. DrawingML contains graphics effects (like shadows and reflection) that can be used on the different graphical elements that are used in DrawingML. In DrawingML you can also create 3d effects, for instance to show the different graphical elements through a flexible camera viewpoint. It is possible to create separate DrawingML theme parts in an Office Open XML package. These themes can then be applied to graphical elements throughout the Office Open XML package.

DrawingML is unrelated to the other vector graphics formats such as SVG. These can be converted to DrawingML to include natively in an Office Open XML document. This is a different approach to that of the OpenDocument format, which uses a subset of SVG, and includes vector graphics as separate files.

Container structure

Office Open XML packages have characteristically different directory structures and names depending on the type of document. An application will use the relationships files to locate individual sections (files), with each having accompanying metadata, in specific MIME metadata.

Office Open XML format uses a ZIP package for storing XML and other data files.

A basic package contains an XML file called [Content_Types].xml at the root, along with three directories: _rels, docProps, and a directory specific for the document type (for example, in a .docx word processing package, there would be a word directory). The word directory contains the document.xml file which is the core content of the document.[Content_Types].xml This file describes the contents of the package. It also contains a mapping for file extensions and overrides for specific URIs.
_rels This directory contains relationships for the files within the package. To find the relationships for a specific file, look for the _rels directory that is a sibling of the file, and then for a file that has the original file name with a .rels appended to it. For example, if the content types file had any relationships, there would be a file called [Content_Types].xml.rels inside the _rels directory.
_rels/.rel This file is where the package relationships are located. Applications look here first. Viewing in a text editor, one will see it outlines each relationship for that section. In a minimal document containing only the basic document.xml file, the relationships detailed are metadata and document.xml.
word/document.xml This file is the main part for any Word document. Viewed in an XML editor, one will see a pretty basic XML file.

Relationships

Relationship files in Office Open XML

An example relationship file (from word/_rels/document.xml.rels)

As such, images referenced in the document can be found in the relationship file by looking for all relationships that are of type http://schemas.microsoft.com/office/2006/relationships/image. To change the used image, edit the relationship.

Hyperlink relations

The following code shows an example of inline markup for a hyperlink:

In this example, the URL is represented by "rId2". The actual URL is in the accompanying relationships file, located by the corresponding "rId2" item. Linked images, templates, and other items are referenced in the same way.

Embedded or linked media file relations

Pictures can be embedded or linked using a tag:

This is the reference to the image file. All references are managed via relationships. For example, a document.xml has a relationship to the image. There is a _rels directory in the same directory as document.xml, inside _rels is a file called document.xml.rels. In this file there will be a relationship definition that contains type, ID and location. The ID is the referenced ID used in the XML document. The type will be a reference schema definition for the media type and the location will be an internal location within the ZIP package or an external location defined with an URL.

Licensing

Whereas the attempt for standardization designates some willingness to publish basic information specifying the subject of standardization, there is no evidence that this approach serves any recognized interest of any third party implementing of the format definition nor does the submission of the proposal include any offer to support such.

Ecma International provides specifications that "can be freely copied by all interested parties without restrictions" and under the Ecma code of conduct in patent matters which requires participating and approving member organisations to make available their patent rights under a reasonable and non-discriminatory basis (see Reasonable and Non Discriminatory Licensing). These "reasonable and non-discriminatory" are common minimum patent conditions for a standard. International standardization adheres to a clear preference for royalty-free patent licensing. That is why Microsoft, which is a main contributor to the standard, provided a Covenant Not to Sue for its patent licensing. The covenant received a mixed reception, with some (like Groklaw) identifying problems and others (such as Lawrence Rosen) endorsing it.

Microsoft also added the format to their Open Specification Promise in which Microsoft irrevocably promises “not to assert any Microsoft Necessary [Patent] Claims against you for making, using, selling, offering for sale, importing or distributing any implementation to the extent it conforms to a Covered Specification ("Covered Implementation")”.

The format can therefore be used under the Covenant Not to Sue or the Open Specification Promise.

In support of the licensing arrangements Microsoft commissioned an analysis from the London legal firm Baker & Mckenzie.

The Open Specification Promise was included in documents submitted to ISO in support of the Ecma 376 fast track submission. In response to criticism of the licensing, ECMA provided the following statements:"

Contributions to Ecma were made under the Ecma Code of Conduct in Patent Matters...

The OSP enables both open source and commercial software to implement DIS 29500."

With Ecma International publishing the specification for free and patents made irrevocably available on a royalty-free basis, Office Open XML conforms to all characteristics of the European Union's definition of an open standard.

Standardization

Standardization within Ecma International

Microsoft submitted Office Open XML to the Ecma International standardization process to make it an open standard. Ecma formed a technical committee (TC45) in order to produce and maintain a "formal standard for office productivity applications that is fully compatible with the Office Open XML Formats, submitted by Microsoft". The technical committee is chaired by Microsoft and includes members from Apple, Canon, Intel, NextPage, Novell, Pioneer, Statoil ASA, Toshiba, The United States Library of Congress, The British Library and the Gnome Foundation ..

Ecma International approved Office Open XML as Ecma standard (Ecma-376) on 2006-12-07 and submitted the approved submission for fasttracking standardization to ISO/IEC JTC 1.

The Ecma-376 Office Open XML File Formats standard can be freely downloaded from Ecma international.

Submission to ISO

As an ISO/IEC JTC 1 external Category A liaison, Ecma have submitted Ecma 376 to the JTC 1 fast track standardization process. To meet the requirements of this process, Ecma have submitted the documents "Explanatory report on Office Open XML Standard (Ecma-376) submitted to JTC 1 for fast-track" and "Licensing conditions that Microsoft offers for Office Open XML".

The fast track process consists of a contradictions phase, a ballot phase, and a ballot resolution phase.

During the contradictions phase, ISO/IEC members national standardization bodies submit perceived contradictions to JTC 1; during the ballot phase the members vote on the specification as it was submitted by Ecma and submit editorial and technical comments with their vote; in the ballot resolution phase the submitted comments are addressed and members invited to reconsider their vote.

Ballot result

ISO announced in September 2007 that the submitted draft of Office Open XML had not achieved the required number of votes for approval during the ballot phase. Eighty-seven ISO/IEC member countries responded to the ballot. There were 51 votes of "approval", 18 votes of "disapproval" and 18 abstentions. "P-members", who were required to vote, had to approve by 66.67% for the text to be approved. The P-members voted 17 in favor out of 32, below the required threshold for approval. Also, no more than 25% of the total member votes may be negative for the text to be approved, and this requirement was also not met since 26% of the total votes were negative. The standardization process then entered its ballot resolution phase, described below.

Response to the ballot

Ecma has produced a draft "Disposition of comments" that addresses the 1,027 distinct NB comments submitted in the letter ballot phase. The ISO/IEC members have 6 weeks to review this draft, and have an opportunity to participate in several informal conference call sessions with the Ecma TC to discuss it before the BRM.

Ballot resolution process

A Ballot Resolution Meeting (BRM) is an integral part of the ballot resolution phase. The outcome of, and period following, this meeting decides whether DIS 29500 succeeds or fails in its bid to become an International Standard. The DIS 29500 BRM is scheduled for the week of 25 February-29 February 2008 at the International Conference Centre Geneva. ISO/IEC has published a FAQ about the meeting.

Final outcome

If the BRM fails to produce an amended text, the fast tracking of DIS 29500 fails and the procedure is instantly terminated (JTC 1 Directives clause 13.10); if however the meeting does produce such a text, the required changes are applied by the editor. In parallel with this, NBs have 30 days after the BRM in which to decide whether to amend their votes of 2 September 2007, and if at the end of this period the ISO voting criteria are met the new text is passed for publication as an ISO/IEC standard (JTC 1 Directives clause 13.9). The final revised text must be distributed no later than one month after the end of the meeting (JTC 1 Directives clause 13.12).

After that, if successful the text goes into the publication process which takes several months. It may take extra time for ISO/IEC to make the standard a free publication, if ever.

Maintenance regime

The precise details of a maintenance regime for OOXML (should it become an ISO/IEC Standard) are yet to be determined. Ecma have however put forward a maintenance proposal.

Whatever maintenance regime is decided, the JTC 1 Directives stipulate that:

Proposals to amend the text, and acceptance of any such amendments, are subject to normal ISO voting processes (JTC 1 Directives clause 15.5)

The standard can't be "stabilised" (i.e. no longer subject to periodic maintenance) except through approval in a JTC 1 ballot (JTC 1 Directives clause 15.6.2).

For the standard to be stabilised it must have passed through 'one review cycle' (JTC 1 Directives clause 15.6.1). In this review cycle the text would have to have been re-written to comply with ISO's formatting and verbal requirements (JTC 1 Directives clause 13.4).

Complaints about national bodies process

Substantial complaints about the procedures in the national bodies have surfaced during the five-month ballot process.

At Portugal's national bodies TC meeting, it was suggested that Sun Microsystems be represented. An unofficial transcript suggested that this was refused for "lack of space". This has been criticized by opponents of OOXML, while Microsoft claims that the number of seats (not chairs) on the committee was limited to 20 by the national body before the meeting.

In Sweden, Microsoft Sweden asked its partners to get involved in the standardization process. In total 22 Microsoft partners (four of which were IBM partners as well) and Google paid a 17.000 SEK fee to join the committee shortly before the decision on Office Open XML. Microsoft also themselves notified SIS that an employee send a memo to two its partners, requesting them to join the SIS committee and vote in favor of OOXML in return for "marketing contributions". Microsoft stated that the memo was the action of an individual employee acting outside company policy, and was retracted soon as it was discovered. In the end, SIS decided to invalidate the vote as one company cast more than one vote, which is against SIS rules.

In Switzerland, SNV registered a vote of approval with comments, there was some criticism about a "conflict of interest" regarding the chairman of the NK 149 committee, who did not allow discussion of licensing, economic and political arguments.

Malaysia's vote is registered as abstain, although its Industry Standards Committee on Information Technology, Telecommunication and Multimedia (ISC-G) voted overwhelmingly No, with comments. The Chief Executive of Sirim had to interfere in the standardization proces after, There has been unprofessional conduct and a lack of ethical standards among some members of the technical committee, and more specifically, some TC/G/4 members had taken to belittling other members who did not share their pro-ODF views, both during committee meetings and in personal blogs. These pro-ODF members were also attempting to short-circuit the normal consensus process for adopting a document standard.

Cyprus was accepted as a P-member a few days before voting, and has been accused of not following a responsible process in analyzing OOXML.

Adoption

OOXML (as specified by Ecma 376) is the default Microsoft Office 2007 format, however Office 2007 is not a 100% conforming application because it still adds structure elements that should be deprecated . For older versions such as Microsoft Office 2000, XP and 2003 a compatibility pack is provided. The compatibility pack can also be used as a stand alone converter with Microsoft Office 97.

On OS X, Microsoft Office 2008 for Mac supports the Office Open XML format.

Microsoft Office Open XML File Format Converter for Mac 0.2 (Beta) Microsoft had previously advised users of Office 2007 to save their files in the old Office binary format.

Microsoft Office Mobile 6.1 upgrade provides support for Office Open XML on Mobile devices.

Apple Inc's iWork '08 suite has read only support for Office Open XML word processing, spreadsheet and presentation file formats in Pages, Numbers and Keynote (respectively).

Apple Inc.'s TextEdit supports Office Open XML in OS X, Leopard.

Apple Inc.'s iPhone has read only support for Office Open XML attachments in emails

Corel has released beta version of their Corel Wordperfect Office X3 edition that includes support for Office Open XML.

Thinkfree Office, the online office suite supports Office Open XML wordprocessing files and will support Spreadsheets and Presentation files in future

Gnumeric has limited SpreadsheetML markup language support.

QuickOffice, a mobile office suite for Symbian and Palm OS, supports Office Open XML.

Novell has created an Office Open XML plugin for the Novell edition of OpenOffice.org. An Office Open XML import filter is slated for inclusion into the OpenOffice.org project.

NeoOffice includes a ODF Converter Plugin that supports Office Open XML documents in the Mac OS X based Office suite based on OpenOffice.org since version 2.1

docXConverter by Panergy Ltd. converts from WordprocessingML to Rich Text Format (RTF) and from SpreadsheetML to Comma-separated values (CSV). docXConverter can be used to transfer WordprocessingML data to other applications that read RTF data such as Word 97.

Dataviz' DocumentsToGo for PalmOS supports Office Open XML documents.

Datawatch supports Office Open XML spreadsheets in its report mining tool Monarch v9.0

Arguments in support and criticism of OOXML standard

Support

OOXML's proponents have provided arguments for standardization, summarized by Microsoft.

In 2007 ODF Alliance India published an extensive technical report containing concrete issues by members of the association and replies from Microsoft.

In December 2007 ECMA has announced, that many of reported issues will be taken into account in next edition of the standardisation proposal to ISO.

User base argument

The most widely used office productivity packages currently rely on various proprietary and reverse engineered binary file formats such as doc, ppt and xls. For users of the binary formats there could be an advantage to migrating to an open XML standard that maps the features of previous binary file formats. Office Open XML for this purpose explicitly states as a goal of the format to preserve investments in existing files and applications.

Protecting Microsoft's Competitiveness

In an interview with ZDNet, Microsoft's senior director of interoperability and IP policy, Nicos Tsilas, expressed concern that IBM and supporters of the Free Software Foundation have been lobbying governments to use the rival OpenDocument Format (ODF) standard exclusively because they are unable to compete with Microsoft through their Office products:

"They have made this a religious and highly political debate," Tsilas said. "They are doing this because it is advancing their business model. Over 50 percent of IBM's revenues come from consulting services."

"Our competitors have targeted this one product - mandating one document format over others to harm Microsoft's profit stream."

"It's a new way to compete. They are using government intervention as a way to compete. It's competing through regulation, because you couldn't compete technically."

Microsoft key benefits arguments

Microsoft makes the following claims about Office Open XML as compared to the format currently used with Microsoft software.

Integration of business information with documents

Open and royalty-free specification

Compact, robust file format

Safer documents

Easier integration

Transparency and improved information security

Compatibility

Policy arguments

Ecma has provided the following policy arguments in favor of standardization with respect to Overlap in Scope with ISO/IEC 26300:2006 (ODF): overlap in scope of ISO/IEC standards is common and can serve a practical purpose; OOXML addresses distinct user requirements; ODF and OOXML are structured to meet different user requirements; OOXML and ODF can serve as duo-standards.

In a statement on February 14, 2007 Microsoft attacked IBM's "global campaign" in opposition to the Office Open XML standardization process. In it, they claim that:

"Ecma almost unanimously agreed to submit Open XML as a standard for ratification by ISO/IEC JTC1 with only IBM dissenting."

"IBM led a global campaign urging national bodies to ... not even consider Open XML, because ODF had made it through ISO/IEC JTC1 first – in other words, that Open XML should not even be thought of on its technical merits because a competing standard had already been adopted. This campaign to stop even the consideration of Open XML in ISO/IEC JTC1 is a blatant attempt to use the standards process to limit choice in the marketplace for ulterior commercial motives – and without regard for the negative impact on consumer choice and technological innovation."

Technical arguments

The use of the Open Packaging specification which allows for Indirection, Chunking and Relative indirection.

Uses the ZIP format, making ZIP part of the standard (Due to compression, files are smaller than current binary formats)

It supports custom data elements for integration of data specific to an application or an organisation that wants to use the format.

It defines spreadsheet formulas.

Office Open XML contains alternate representations for the XML schemas and extensibility mechanisms using RELAX NG (ISO/IEC 19757-2) and NVDL (ISO/IEC 19757-4)

No restriction to image, audio or video types. Images can be in WMF, GIF, PNG, TIFF, PICT, JPEG or any other image type, Book 1 §14.2.12.

Embedded controls can be of any type, such as Java or ActiveX, Book 1 §15.2.8.

WordprocessingML font specifications can include font metrics and PANOSE information to assist in finding a substitution font if the original is not available, Book 3 §2.10.5.

Alternate Content Block, a solution to define alternate content (like an image) that can be used in various situations where a consuming application might not be capable of interpreting what a producing application wrote, Book 3 §2.18.4.

Internationalization support. For example date representation: In WordprocessingML (Book 4 §2.18.7) and SpreadsheetML (Book 4 §3.18.5), calendar dates after 1900 CE can be written using Gregorian (three variants), Hebrew, Hijri, Japanese (Emperor Era), Korean (Tangun Era), Saka, Taiwanese, and Thai formats. Also, there are several internationalization related spreadsheet conversion functions.

Custom XML schema extensibility allowing implementations to the format with features. That can for instance facilitate conversion from other formats and future features that are not part of the official specification yet.

The format has design features that can be used to enhance performance. for instance * SpreadsheetML has an optional performance feature to track which cells have to be recalculated when spreadsheet data changes. In spreadsheet formats lacking this feature you always have to verify all of the used cells in the entire spreadsheet at least once for recalculations of the spreadsheet.

Criticism

The standard has been the subject of wide and varied debate in the software industry. Many of the participants in the approval process are typically supportive of eventual ISO standardization, but are unwilling to support the ISO fast track process until their issues are resolved. Over 6000 pages long, the specification is difficult to evaluate quickly. The existence of the OpenDocument format (ISO 26300:6000) raised the issue that there is overlap with this standard. Critics suggest Microsoft adopt the OpenDocument standard as its default format for future versions of Office. Objectors also complain that there could be user perplexity regarding the two standards because of the similarity of the "Office Open XML" name to both "OpenDocument" and "OpenOffice".' Microsoft, whose products use the current version of Office Open XML has not committed to use the specification for any length of time. But according to a Techworld article, "to organisations that need a well-defined, XML-based format to manage huge numbers of documents that may be archived for decades, this is important. These customers want a standard that Microsoft will promise to use - even if it's not convenient for the company's plans." Brian Jones, the Microsoft manager working on OOXML in his blog stated "We'll of course stay active and propose changes based on where we want to go with Office 14. At the end of the day, though, the other Ecma members could decide to take the spec in a completely different direction. Now my impression is that won't happen, as the folks on the TC all have pretty similar visions for the future of the spec, but since it's not guaranteed it would be hard for us to make any sort of official statement."

Sources of criticism

Criticism originates from a wide variety of organizations and individuals, including the free software and open source communities, FFII, OpenDocument supporters and major industry players that develop Office software around OpenDocument, such as Sun Microsystems, Novell, IBM, and Google.

Office Open XML has been widely criticized by these organisations on technical and legal grounds.

There is also criticism that the proposed standard overlaps with OpenDocument, which is standardised as ISO/IEC 26300:2006.

In addition, the standardization process itself has been questioned, including with regard to balloting irregularities by some technical committees, Microsoft representatives and Microsoft partners in trying to get Office Open XML approved. FFII launched a campaign against this standard.

Technical criticisms

Reliance on application-defined behaviors to support important functionality that should be documented or supported via existing standards. Book 4 §6.1.2.19 defines the "equationxml" attribute of "shape" elements, "used to rehydrate an equation using the Office Open XML Math syntax"; however, the "actual format of the contents of this attribute are application-defined"..

Ecma has proposed solving this issues by adding on the lacking syntax of this element and encourage the use of an open format for the embedded math like the specs onw OMML or the w3C's MathML formats

Locale conventions (such as decimal points, date formats, and character settings) are inconsistent. SpreadsheetML documents are internally represented in the US English locale, but font types such as "bold" can be specified in any language (e.g. "gras" in French), although the specification does not provide a list of equivalents in different languages..

Non-standard language codes and color names.

Ecma has proposed solving the language issue by adding support IETF BCP 47 for representing languages during the ISO standardization process.

SpreadsheetML stores dates in decimal time as the number of fractional days since 1900. It incorrectly treats 1900 as a leap year in order to remain backward compatible with previous versions of Microsoft Excel and Lotus 1-2-3. The criticism is twofold; only dates after the nonexistent Gregorian date 1900-02-29 can be used, and it ignores the ISO 8601 standard for the representation of time and date.

Ecma has proposed solving this issue by adding support for ISO 8601 during the ISO standardization process.

Use of DrawingML and the deprecated VML instead of SVG, and use of Office Math ML instead of MathML. MathML and SVG are W3C recommendations. VML was rejected as a W3C standard in 1997.

Internal inconsistencies and omissions. Book 4 §2.18.4 lists styles such as "apples", "scaredCat", and "heebieJeebies", but does not fully define these styles. Missing properties include height, width, color depth, and orientation.

Inconsistent notations for percentage units. Book 4 §2.18.85 uses predefined symbols (like "pct15" for 15%) in 5 or 2.5 percent increments, §2.15.1.95 uses a decimal number giving the percentage, §2.18.97 uses a number in fiftieths of a percent, and §5.1.12.41 uses a number in thousandths of a percent.

Inflexible numbering format. Book 4 §2.18.66 describes a numbering format that is fixed to a few countries and contradicts both the W3C XSLT recommendation and Unicode ISO 10646 standard.

Non-standard, inflexible paper size naming. Book 4 §3.3.1.61 define a "paperSize" attribute for which values 1 through 68 are predefined standard paper sizes such as A4 paper.

Non-extensible bitmasks, some elements attributes are defined as bitmasks. Book 4 §2.8.2.16 "sig (Supported Unicode Subranges and Code Pages)" describes the element, the attributes of which are all bitmasks. The bitmask actually represent values in ISO standards IS 9541-4 or 14496-22

Legacy document rendering compatibility is identified using (deprecated) tags. Book 4 §2.15.3.6, "autoSpaceLikeWord95", “useWord97LineBreakRules”, “useWord2002TableStyleRules", and §2.15.3.31, "lineWrapLikeWord6", and "suppressTopSpacingWP" for a 16-year-old version of WordPerfect. These behaviors are not properly documented in the OOXML specification. (These items should only occur in OOXML documents that were converted from predecessor Microsoft Office documents).

Ecma has proposed a twofold solution in their dispostion of comments. Firstly the compatiblity tag will be documented more extensivly so their behaviour can be more faithfully reproduced if needed and secondly these deprecated items will be taken from the formal specification and moved to an annex.

Accessibility issues according to University of Toronto, such as form fields not being associated with their labels, absence of a tabbing order for forms, and boundaries in the use of alternative text descriptions of objects.

Editorial criticisms

More than 10% of the examples used in the WordProcessingML part of the specification (300 of 2300) do not validate against the schema, signifying that the examples in specification have not been reviewed enough prior to becoming an Ecma standard

Errors in the spreadsheet formula specifications confirmed by Microsoft.

Examples use the Windows path convention, instead of the platform-neutral URI convention

The behavior of some OOXML attributes are undefined, or only defined by example