Benefits of the Microsoft Office Open XML File Formats

An XML Node Tree
An XML Node Tree

This article discusses the distinctions between the old and new Microsoft Office file formats, and explains the advantages of choosing the new formats, which are called the Office Open XML file formats. Confusingly, the Office Open XML formats are not the same as the OpenOffice XML file formats. The naming similarity causes much confusion, and arises from the fact that the goals of both definitions were similar, even though the implementations are distinct.

This article also explains how you can decompress a Word file that has been stored using the new XML format and examine its content directly. This can sometimes be helpful if you find that you cannot open a file because it has been corrupted, in which case you may be able to fix the error and make the file once again editable.

In an earlier post, I mentioned the new file format for Microsoft Word files (i.e., files with a .docx extension), which stores data using XML, instead of the binary data coding that was used by the original Microsoft Word format (files with a .doc extension). In fact, that is true not only for .docx files, but also for various other file types created using recent versions of Microsoft’s Office suite of programs. For example, Microsoft Excel files have a new .xlsx format, replacing the older .xls format.

In my earlier post, I also mentioned the general dangers of using proprietary file formats (for any application), because the data contained in the files can only be accessed via the one specific application that’s designed to open files in that format. If the application becomes unavailable, or if the manufacturer changes the program to the point where it is no longer able to open files that use its own older formats, you may have no way to access data in files with the proprietary format. This could result in a severe loss of data at some future time.

To avoid this situation, it’s better whenever possible to store data using open file formats.

Just in case you think that, by extolling the advantages of the Office Open XML file formats here, I’m acting as a “shill” for Microsoft, rest assured that I’m not. In fact, if you read on, you’ll discover why using these new formats can actually free you from dependence on Microsoft’s applications.

Office Productivity Suites

Over the years, it has become apparent that certain types of application program have widespread usefulness in office environments across many industries. The exact list varies, but in general the following program types are used by typical office computer users:

Typical Components of an Office Software Suite
Typical Components of an Office Software Suite
  • Word Processor
  • Spreadsheet
  • Email Client
  • Slide Show Generator
  • Vector Drawing

Software manufacturers have grouped together these commonly-used programs, and offer them as “office productivity suites” with varying levels of integration between the component programs within the suite.

Most computer users will be aware that the Microsoft Office suite is still the most widely-used office productivity suite in the world (see, for example,

The continued popularity of Microsoft Office is perhaps surprising, because the software is by no means free, and in fact there are good-quality free alternatives available. In this article, I won’t discuss the psychology of why so many people continue to pay to use a piece of software when there are equivalent free alternatives available. However, I will mention some of the alternatives, and show you how the Open XML file formats allow you to use those more easily.

Incidentally, it’s not my intention in this article to discuss the general use of Office suite software in “IT” environments. I don’t work in the field of “IT” (in the sense that the term is typically used), but I do use Office suite software in my roles as author and programmer.

Why were the XML Formats Developed?

I haven’t found any clear statement of the motivation that prompted Microsoft to consider replacing its long-standing binary file formats with XML-based formats. However, I suspect that the primary motivations were competition and pressure from large users of the Office suite.

Given the prevalence of Microsoft Office on computer systems around the world, around the year 2000, many government and official bodies were becoming concerned about the amount of vital information that was being stored in files using the Microsoft binary formats. The problem wasn’t merely the risk that files could become corrupt or unreadable. There was also concern that it was impossible to be certain that the proprietary data formats didn’t include “back doors” that would permit the reading of content that was supposed to be secure.

At the same time, open-source software was being developed to provide free alternatives to the more popular applications in the Microsoft Office suite. The most prominent of these open-source suites was OpenOffice, developed by Sun Microsystems. Although OpenOffice supported the Microsoft binary file formats, it also had its own set of XML-based formats, conforming to the public OpenOffice XML standards.

As a result of these developments, Microsoft offered its own version of open XML-based format specifications, and sought international certification of those formats. The result is that both sets of standards are now publicly available.

Advantages of the XML Formats

  • Files are more compact. In most cases, if you compare the size of an Office file saved in the binary format, with the same file saved in the equivalent Open XML format, the XML-formatted file will be smaller. This is largely because of the compression applied to the Open XML files. However, files that contain a large number of graphics may not be smaller, because the graphics cannot be further compressed by the zip algorithm.
  • Easier corrupted file recovery.
  • Easier to locate and parse content.
  • Files can be opened and edited with any XML editor.
  • Files containing macros are easier to identify.

Formats & Applications

The Office Open XML formats correspond to the Office applications as shown in the table below:

Office File Formats
Office File Formats

How To Examine the Contents of a Word docx File

When you use Word (or an equivalent word processor) to open a file that uses one of the XML file formats, such as a Word docx file, all you see is a view of the document itself, complete with all its formatting. There seems to be no evidence of any XML structure.

If this is an XML-encoded file, then where is the XML? How do you actually access the XML that defines the document?

In fact, all files that use any of the Office XML formats compress all the XML and component parts into one “zip” file. You can, of course, compress other files into “zip” files, but, when you do, the resulting file typically has the extension .zip.

In fact, Office XML files are indeed zip files, and can have a valid .zip extension. To be able to view and even extract the internal XML and other components, you simply have to open the file using a zip extraction program, instead of a Microsoft Office program. In Windows, the easiest way to do that is to give the Office file a .zip extension.

The following procedure explains exactly how to do this under Windows. Note that this is not an “undocumented hack”; Microsoft encourages you to access the components of the documents this way. These instructions are available from Microsoft at:

  1. Add a .zip extension to the end of the file name, before the .docx
  2. Double-click the file. It will open in the ZIP application. You can see the parts that comprise the file.
  3. Extract the parts to the folder that you created previously.

Non-Microsoft Support for the XML Formats

Many people seem to assume that, if they receive a file in one of the Microsoft Office file formats (either the older proprietary formats or the newer XML formats), then they must use Microsoft Office to open and edit it.

In fact, that’s not true, because the available competitor office suites can handle many of the Microsoft formats well. OpenOffice and Libre Office can both edit files in many of the Microsoft Office formats. Additionally, modern versions of Microsoft Office can at least open files in many of the OpenOffice XML formats, even if it does not fully support them. (In all cases there may be minor formatting differences, and you shouldn’t swap between formats unnecessarily.)

Thus, using the new Office Open XML file formats does not restrict you to using only Microsoft-supplied applications. Files in these formats can be expected to be reasonably “future-proof” for a long time to come.

Deficiencies of the Office Open XML Formats

I am not aware of any major deficiencies of the new formats that would dissuade anyone from using them in preference to the previous binary formats. Here are some relatively minor issues to consider:

  • Some files containing large quantities of graphics may be larger than in the equivalent binary format.
  • Files in the new Open XML formats cannot be opened using old (pre-2007) versions of Office.
  • The XML structure is such that it’s not easy to parse the content of the files in useful ways.

Structure Example

Here’s an example of the actual Word XML markup for a very simple text document. The example shows how revisions to the markup are stored in the file, which can make it difficult to parse the XML content to extract meaningful information.

I wrote a very simple text file, which includes the line of “Normal”-styled text: “This is just a test.”.

In the WordML XML, this appears as:

<w:r><w:t>This is just a test.</w:t></w:r>

Next, I deliberately introduced a revision, by typing some extra characters before the final “t” of “test”, then deleting the extra characters and saving the result. The resulting XML looks like this:

<w:r><w:t>This is just a tes</w:t></w:r><w:bookmarkStart w:id="0" w:name="_GoBack"/><w:bookmarkEnd w:id="0"/><w:r w:rsidR="0000364D"><w:t>t</w:t></w:r><w:r w:rsidR="003F3CE4"><w:t>.</w:t></w:r>

As you can see, the final “t” and the period are now in separate <w:t> elements, and a new bookmark has been inserted. This type of element-splitting makes it difficult to extract the actual text from the XML.

Therefore, before attempting any processing of an Office Open XML-formatted file, you should always “Accept all changes” to eliminate version-tracking markup.


  • Always use the new XML Office formats rather than the old binary formats when possible.
  • Even if you have Microsoft Office installed, consider installing LibreOffice, etc., on the same computer. You’ve nothing to lose.

Software Quality: The Horror of Spaghetti Code

Spaghetti Code Spook looming out of graveyard babbling about GotosWhen scanning the news, I often see articles with titles such as, “The nation needs more programmers”, “The nation needs to increase the number of STEM graduates”, and so on. However, this is a simplistic idea for many reasons. I don’t plan to examine all the reasons in this article, but I do want to discuss the notion that “any kind of programming will do” and explain the reasons to avoid Spaghetti Code.

It seems that most non-programmers simply assume that “all programs are created equal”, in the sense that all code is of equivalent quality. Unfortunately, that is by no means the case. To be clear, the quality of the code has nothing to do with whether the intention of a program is “good” or “bad” (i.e., malware). A malicious program may be of very high quality, whereas a well-intentioned program may be badly written.

Recognition of the problems caused by poor quality programs over the past few decades has led to advances in the structure of programs. These structures are not necessary for the correct operation of a program, but they make the program much easier for humans to understand and maintain, and thus the code has much greater and more enduring value.

The Evolution of Programming Structure

Largely as a result of bitter experience, the discipline of programming has evolved rapidly over the past few decades. Some code that conforms to what was considered acceptable programming practice in, say, the 1980s would be regarded as appallingly inept today.

In the early days, it was considered sufficient just to write code that produced the desired result. There was very little consideration of how the code was implemented, and in any case the available coding tools were quite primitive.

However, it soon became apparent that merely having code that worked wasn’t adequate, because sooner or later the code would need to be modified. If the code had been implemented in a disorganized way, possibly by a programmer who had since moved onto other projects, the maintenance task became nightmarishly difficult. This realization led to the development of the principles of Structured Programming, then Object-Oriented Programming, and other more sophisticated approaches.

There isn’t space in this article to discuss the detailed history of programming structures and paradigms. For much more detail, see, for example, Here, I just want to provide an example of why programming structure is so important.

Early programming languages had very limited control structures. Perhaps the most common situation in program writing is when the code must perform a test, and then take actions based on the result of the test.

The earliest programs were written in machine code. Even the use of Assembly code (which used mnemonics to describe machine instructions) offered limited control structures, which usually consisted of jumping to one code address or another, depending on the result of a test.

“High Level Languages” were created to make programming more efficient, and to offer more sophisticated control structures. However, some high-level languages still retained the GoTo instruction, which permitted unstructured jumps in the control flow.

When an error was discovered, or when it became necessary to change the code’s operation, the existence of all these jumps made it very difficult to trace through the sequence of programming steps. For obvious reasons, such code has come to be known as Spaghetti Code. If you see code that contains such instructions such as GoTo or GoSub (used in Visual Basic), then you’re probably looking at Spaghetti Code.

The deficiencies of Spaghetti Code led to the development of Structured Programming, where code is divided up into clearly defined modules, and control flow is determined by looping and branching constructs that make it much easier to follow the operation of a program. Later on, more sophisticated programming paradigms were developed, such as Object-Oriented Programming. These paradigms not only eliminated the Spaghetti Code, but also offered other advantages. The important point is that these paradigms were developed to make programming easier and more productive, so it really isn’t the case that writing Spaghetti Code is somehow simpler.

Not The State of the Art: A Horrifying Example of Spaghetti Code!

I’d like to be able to state that spaghetti code and its attendant nightmares are nothing but memories of the past, and that nobody would dream of writing Spaghetti Code today.

Unfortunately, that’s not universally true, and I still sometimes encounter such code today, as in the following example written in the Microsoft VBA (Visual Basic for Applications) language, which was intended for processing the content of Microsoft Word documents.

Lest you think that the following example is something I made up (“Surely nobody would really write code like this”), I assure you that this is real code that I excerpted from a VBA program that was being relied on by many users. All that I’ve done is to change some function and label names, to protect the guilty!

The purpose of this function is to find and select the first heading in a Word document (that is, the first paragraph of text with any of the styles Heading 1 through Heading 9). When this heading has been found, the code checks to see whether it contains the text “Heading Before”. If it does, the code jumps to the next heading in the document, and examines the style of that heading. If the style of the following heading is not “Heading 1”, then a new Heading 1-styled heading is inserted, with the text “Heading Inserted”. (Don’t worry about why it would be necessary to do this; rest assured that this was claimed to be necessary in the code on which I based this example!)

Notice particularly the statement GoTo InsertHeadingOne and its associated label InsertHeadingOne.

Sub insert_Heading1()
	Call Select_First_Heading_in_Doc
	With Selection
		If .Paragraphs(1).Range.Text Like "Heading Before" Then
			.GoToNext what:=wdGoToHeading
			GoTo InsertHeadingOne
			If Not .Paragraphs(1).Style = "Heading 1" Then
				.TypeText vbCr & "Heading Inserted" & vbCr
				.Paragraphs(1).Style = "Normal"
				.Paragraphs(1).Style = "Heading 1"
			End If
		End If
	End With
End Sub

This is such a short subroutine that an experienced programmer would think it should be possible to write it without GoTo instructions and labels. That is correct; it is possible, and the result is much more succinct, as I show below.

Let’s examine the subroutine’s control flow. The code selects the first text in the document that has any Word “Heading” style. Then, it evaluates the “If” statement. If the evaluation is true, then the selection is moved to the next heading, following which the “Else” code is evaluated! In other words, the code within the “Else” clause is executed whatever the result of the “If” expression, and thus doesn’t need to be within an “Else” clause at all.

The following code is functionally identical to that above, but does not require either GoTo instructions or the spurious “Else” clause.

Sub insert_Heading1()
	Call Select_First_Heading_in_Doc
 	With Selection
		If .Paragraphs(1).Range.Text Like "Heading Before" Then
			.GoToNext what:=wdGoToHeading
		End If
		If Not .Paragraphs(1).Style = "Heading 1" Then
			.TypeText vbCr & "Heading Inserted" & vbCr
			.Paragraphs(1).Style = "Normal"
			.Paragraphs(1).Style = "Heading 1"
		End If
	End With
End Sub

This example gives the lie to the excuse that “we have to write spaghetti code because it’s more compact than structured code”, since the structured and well-organized version is clearly shorter than the spaghetti code version.

This example doesn’t include the use of the GoSub instruction, which is another “relic” from pre-structured programming days. GoSub offers a very primitive form of subroutine calling, but should always be avoided in favor of actual subroutine or function calls.

The Race to the Bottom

The issue of software quality frequently sets up an ongoing conflict between programmers and clients (or between employees and employers).

Clients or employers want to produce working code as quickly and as cheaply as possible. The problem with this is that it’s a short-sighted approach that frequently turns out to be a false economy in the long term. Cheap programmers tend to be inexperienced, and so produce poor quality code. Rushing code development leads to implementations that are not well thought out. The result of the short-sighted approach is that the code requires a disproportionate level of bug fixing and maintenance, or else has to be rewritten completely before the end of its anticipated lifetime.

Avoiding the Horror of Spaghetti Code

In summary, then, the message I want to offer here is this. If you’re going to write software, or hire someone else to write software for you, then you should make it your business to understand what constitutes high-quality software, and then take the time, effort and expense to ensure that that is what gets produced. Unfortunately, I realize that many software producers will continue to ignore this recommendation, but that doesn’t make it any less true.