i4i xml patent, #5787449

Filed 1994, granted July 1998. The Canadian company i4i won a $200-million judgment against Microsoft. Many of the court papers are here.

Here is what the patent claims:

A system and method for the separate manipulation of the architecture and content of a document, particularly for data representation and transformations. The system, for use by computer software developers, removes dependency on document encoding technology. A map of metacodes found in the document is produced and provided and stored separately from the document. The map indicates the location and addresses of metacodes in the document. The system allows of multiple views of the same content, the ability to work solely on structure and solely on content, storage efficiency of multiple versions and efficiency of operation.

Despite the italicized phrase, the patent application suggests that at the time of invention the i4i claim was all about a perceived improvement on the existing practice of mixing tags and content inline:

For manual production of documents the intermingling of the markup codes with the content is still the best way of communicating structure. For electronic storage and manipulation it suffers from a number of shortcomings.

Yet further, there is a difficulty of resolving the markup codes from the structure. Markup codes have to be differentiated from the content stream they are a part of. This involves designating `special` characters or sequences of characters which should be identified and acted upon. This complicates the task of any routine which must work on the document.

This is incredibly basic. It is fundamentally not an issue. The only claimed improvement for the i4i approach is processing speed:

The present invention provides also for efficiency of operation on the document. The invention allows document operations to be much more efficient. It is no longer necessary to parse the entire document to locate the embedded codes. Differentiating codes from content is obviously no longer a problem since they are held in different areas. This also allows more efficient coding strategies to be developed without the restriction of ensuring that all codes are clearly differentiated from any possible content.

A further patent claim highlighting the concept of separation.

Thus, in sharp contrast to the prior art the present invention is based on the practice of separating encoding conventions from the content of a document. The invention does not use embedded metacoding to differentiate the content of the document, but rather, the metacodes of the document are separated from the content and held in distinct storage in a structure called a metacode map, whereas document content is held in a mapped content area.

It is not unreasonable to believe that somehow i4i's initial patent claims got progressively inflated by the time the case reached the court. They may have claimed their method covered any editing of xml in such a way as to offer editing of either the content or the structure separately. Alternatively, Office 12 did include a feature (the XML Data Store) in which some xml could be included in the files that would affect the format of the remaining document; this might have been the "data structure" that represented "distinct storage" of the "metacode map". Still, i4i's patent is actually about how to maintain the "metacodes" (XML markup tags) separately from the document content, for efficiency reasons; using one xml file to affect how another xml file determines a document layout is an entirely different thing.

It is admittedly a logical chain from the idea of separating data and tags to the idea of separate editing of data and tags. But that chain does not appear to be in the patent. Furthermore, at one point, in discussing using metacode maps for multiple document views, i4i acknowledges prior art:

In SGML this ability to overlay two or more structures on a single set of text is called Concur. Its usefulness has long been recognized but it has proven difficult to implement

More generally there is this principle:

Embedded codes are prior art

There is a detailed example in the i4i patent application as to how to convert the following:

<Chapter><Title>The Secret Life of Data</Title><Para>Data is hostile.</Para><Para>The End</Para></Chapter>

Pointers need to be drawn from the metacode-map entries below to the corresponding points in the content on the righthand side. Each tag in the metacode map is followed by a list of pointers into the content.

metacode map
 content    
<Chapter>   [1]
<Title>        [1]
</Title>       [2]
<Para>        [2] [3]
</Para>       [3] [4]
</Chapter> [4]
 [1]The Secret Life
of Data[2]Data is
hostile.[3]The End[4]

Block diagrams from the patent application are here.

The Markman Hearing

This is the court's decision on how the claims are to be interpreted. The full ruling is here; here are some quotes. Overall, they do not go very well for Microsoft.

“metacode[s]” means “an individual instruction which controls the interpretation of the content of the data.”

Note this is a broad interpretation, as opposed to "a data modifier that is stored in a separate structure".

In total, the intrinsic record does not rebut the presumption that “mapped content” and “raw content” have different meanings. Further, the intrinsic record indicates “raw content” is a subset of “mapped content,” and “mapped content” does not need to be free of all metacodes.

For the above-mentioned reasons, “mapped content” means “the content of a document corresponding to a metacode map.” “Metacode map” and “map of metacodes” mean “a data structure that contains a plurality of metacodes and their addresses of use corresponding to a mapped content.”

Finally, note this claim:

However, the disclosed algorithms create and store the metacode map and mapped content in “storage space” and do not require separate files for the metacode map and the mapped content.

Wasn't separate storage the whole point of the original patent?


I4I did indeed "invent" something. But what they invented was essentially the idea that some customers wanted to edit text documents that had an underlying XML structure. Once you realize that customers might pay for that, the creation of the actual product is obvious. This is very similar to the NTP v RIM case.

The part about "separate manipulation of the architecture and content of a document" sounds deep, or at least nontrivial, except that the patent application itself strongly suggests that the invention is really just about a specific implementation technique for separating archictecture from content.  Virtually all flavors of xml use embedded tags, <foo>like this</foo>. The whole point of the i4i patent is that it doesn't use embedded tags.

On the other hand, there are suggestions that Microsoft did in fact develop a format for creating "custom XML schemas" that used the i4i method. Any xml schema that lets you set the tag values in one place and one place only, as opposed to doing a global search-and-replace, could be said to violate the spirit of the i4i patent.

Still, it is a stretch, to say the least, to believe that the i4i patent covers all custom XML schemas.

The following is from the blog of an Office product manager at Microsoft, Brian Jones, http://blogs.msdn.com/brian_jones/archive/2005/11/04/integrating-with-business-data-store-custom-xml-in-the-office-xml-formats.aspx.

XML Data Store

In Office 12, we've introduced a new feature to the formats that we're currently calling the XML data store, and the way it works is really simple. As you should all know by now, the new format consists of a ZIP file with a bunch of XML parts (files) inside. Up until now we've talked about all the parts that we in Office have defined to create our documents. You as a developer also have the ability to add your own parts though. You can take any XML file and put it inside the ZIP package. Then all you need to do is create a relationship from the main document part to your XML part, and the Office applications will roundtrip your XML with the file, which means:

Roundtripping your data: The ability to put your XML in the ZIP package means that you now have a place to store any data your solution may need. The data will travel with the document, but will always be stored as a separate XML part in the ZIP package. This means it's really easy to get to and modify without dealing with any of the application's data....

Separating data from the document: As well, because the information is stored in the data store, you benefit from the fact that the user cannot directly edit your data by editing the document (they can’t accidentally delete part of your data, since it’s stored separately.

This is kind of vague; a more concrete example can be found at http://msdn.microsoft.com/en-us/library/bb510135.aspx. (Another article on this feature is at http://openxmldeveloper.org/blog/b/openxmldeveloper/archive/2010/10/27/59361.aspx.) Note that it indeed allows a separate XML area that is connected to the main document only via tags. However, the original i4i patent appeared to involve using the separate area for tag values; the Microsoft strategy on the face of it is for a separate area for entire XML files. The last paragraph is all about the real-world importance of separating the tags and storing them elsewhere.

See also Joe Wilcox's article at www.betanews.com/joewilcox/article/Is-Microsoft-violator-or-victim-in-i4i-patent-dispute/1250119565, in which he suggests that the Microsoft customers most interested in this new Office feature were those in the pharmaceuticals industry, which is exactly what i4i writes software for.

At the page www.afterdawn.com/news/article.cfm/2009/08/13/update_microsoft_knew_about_i4i_s_xml_patent, there is an alleged quote from Microsoft "newly leaked emails":

"We saw [i4i's products] some time ago and met its creators. Word 11 will make it obsolete," said one email from Martin Sawicki, a member of Microsoft's XML for Word development team.

That would make the '449 a defensive patent: one where the purpose is not to be a patent troll, but instead to allow you to launch defensive attacks against competitors that horn in on your market. This does not legitimize the patent completely, but does put it in a different context.

An excellent technical blog on the '449 patent is at http://broadcast.oreilly.com/2009/08/mircrosoft-and-the-two-xml-pat.html. There's a good example of what metacodes are all about, but also a somewhat cryptic discussion of point tags (like <b> in html) versus range tags (like <title> ... </title>, strictly hierarchical).


MS information on how the editing works: http://msdn.microsoft.com/en-us/library/aa212889%28office.11%29.aspx.

It appears to be true that Microsoft intended to take i4i's broader idea -- supporting the structural editing of XML-based documents -- and thus to take over i4i's business niche.

Somehow, i4i convinced a jury in East Texas that their patent covers any editing of XML, so as to preserve the structure. This is what Office 12 did.

What of the jurors? Did they really think i4i's patent covered what Microsoft did, or did they think that Microsoft was trying to crush a competitor "unfairly"? Here are some quotes from the jurors, at http://thepriorart.typepad.com/the_prior_art/2010/01/jurors-from-i4i-v-microsoft.html:

Juror BG: “I felt that i4i had a really strong case,” she says. “It was evident that Microsoft knew that [i4i] had a patent," and still decided “all of a sudden” to create its own version.

Juror JS:  This juror noted that MS had met with i4i at one point: "[Microsoft] got their foot in the door and got enough information, and then took it.” JS also seemed concerned about Microsoft's lack of vigor in pursuing the case. "Two hundred million dollars seems to me like a great amount of money…I would think if I was Bill Gates, and had $200 million on the line, I would want to be present.”

Juror BC: “It was very plain and very clear, throughout the testimony that what Microsoft said and did wasn't right”

What did Microsoft do wrong?


After the jury verdict, Microsoft petitioned the District Court for a "Judgment as a Matter of Law" (JMoL), meaning that they wanted the judge to declare that the jury verdict contradicted the existing law in the case; that is, to find "there is no legally sufficient
evidentiary basis for a reasonable jury to find as the jury did." A high standard has to be met here, but this is indeed the appropriate avenue if the jury misunderstood the patent. However, the judge also misunderstands the patent; he wrote (in http://pld.cs.luc.edu/ethics/i4i_v_microsoft_district_jmol.pdf)

The ‘449 patented invention created a reliable method of processing and storing content and metacodes separately and distinctly. The data structure primarily responsible for this separation is called a “metacode map.” According to the patent, the “metacode map” allows a computer to manipulate the structure of a document without reference to the content. [p 2]

The metacode map is a data structure that once upon a time might have saved some computing resources, but which is trivial to work around by leaving the tags "in place" in the document. The metacode map has nothing to do with the idea of manipulating the XML structure without referring to the content, except in that it might suggest one possible way to do that.

However, here's the district court opinion on data structures:

First, Microsoft argues that i4i presented no evidence that the accused WORD products created “a data structure” as required by the Court’s construction of the claim term “metacode map.” The Court construed and instructed the jury that “metacode map” and “map of metacodes” in the ‘449 patent meant “a data structure that contains a plurality of metacodes and their addresses of use corresponding to mapped content.” The Court further construed “mapped content” as meaning “the content of a document corresponding to a metacode map.”

Essentially, i4i managed to claim that any way of storing "metacodes", including embedding them in the body of the document, amounts to storing them in a "data structure" as covered by the patent. Even though the stated point of the patent was that this data structure be "separate".

During trial Dr. Rhyne, one of i4i’s technical experts, explained that the meaning of “a data structure” was “a physical or logical relationship among data elements designed to support specific data manipulation functions.”

In other words, embedded XML tags would now be a "data structure" too.

All this suggests that i4i has figured out how to expand their original claims. The expanded claim is clearly still tied to the invention, and so the court elected to uphold it, but the expansion so waters down the original idea as to turn it into something genuinely obvious.

Maybe Microsoft's core problem is that they were not able to find a short and comprehensible way to say the following:

    embedded codes are prior art.


Microsoft appealed the case to the Federal Circuit, and then to the Supreme Court. But you cannot appeal a finding of fact as to claims interpretation [pld: some issues of claim construction can be appealed; I'm still working on why Microsoft did not prevail here.]

The issue MS brought to the Supreme Court was the fairness of the presumption that patents were valid, which thus required "clear and convincing evidence" to overturn a patent. The Supreme Court upheld this standard, though they did agree that in the case of prior art that had not been previously considered by the patent office then a weaker "preponderance of evidence" standard could apply. But that didn't help Microsoft, which probably wanted a new trial in order to give their legal arguments a second hearing.

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