Working with Numbering in Open XML WordprocessingML

EricWhite — Tue, 15 Dec 2009 22:44:00 GMT

[Blog Map]

Update Dec 15, 2009: This is the 8th in a series of posts on implementing a transform of WordprocessingML to XHtml.

1) Transforming Open XML Word-Processing Documents to XHtml

2) Transforming Open XML Word-Processing Documents to XHtml (Post #2)

3) Transforming Open XML Word-Processing Documents to Html (Post #3)

4) Open XML WordprocessingML Style Inheritance

5) Comparison of Html/CSS Tables to WordprocessingML Tables

6) Assembling Paragraph and Run Properties for Cells in an Open XML WordprocessingML Table

7) Implementing 'Inheritance' in XML

8) Working with Numbering in Open XML WordprocessingML

When implementing a conversion of Open XML word processing documents to HTML, one of the interesting issues is accurately converting numbered and bulleted lists. You must pay special attention to them, because they impact the text that the document contains, but that text isn't directly in the markup. If you are accurately extracting the text of the document, you must process some elements and attributes to assemble the correct text.

Numbered items and bulleted lists are not trivial, and justifiably so. There are a large number of features of numbered and bulleted lists, each used by a different set of users. These features are represented by elements in the markup. However, you don't need to pay attention to all elements. Some aspects of the markup are there just to affect the user interface, and you don't need to pay attention to those elements when determining the textual representation of a numbered or bulleted item. This post presents just the essentials that you need to know to work with numbered and bulleted items.

Note: This blog post is an MSDN article that I've written. It will be published on MSDN sometime in the near future. Thanks to Tristan Davis, Zeyad Rajabi, and Brian Hyams for tech reviewing this post.

The easiest way to talk about numbering markup is to relate the markup to the user interface of Word. You are concerned only with the document modifications that we can make with these three buttons:

There is a fair amount of indirection for WordprocessingML numbering markup. There are three patterns for this indirection in the markup:

Direct numbering for simple numbered or bulleted lists
Style based numbering, i.e. Heading1 is at the first level of indentation, Heading2 is at the second level of indentation, etc.
Named numbering styles

I'll examine each of these patterns in depth.

Markup for a Simple Numbered List

First, I'll show the markup that is generated if you create a simple numbered list:

So that I can discuss the markup accurately, I need to make an important distinction between two aspects of numbered or bulleted lists. For each numbered or bulleted item, there are two components – the list item, and the paragraph text:

We need to make this distinction because the list item is what we need to assemble for each paragraph. In addition, there is separate formatting markup for the list item. The same distinction applies to a numbered list:

The following diagram shows the indirection for a simple numbered or bulleted list:

I'll examine the markup for the following simple numbered list:

The markup in the main document part looks like this:

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="0"/>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>Paragraph one.</w:t>

</w:r>

</w:p>

The w:numPr element contains the numbering elements that we're concerned with. The w:ilvl element is a zero based number that indicates the indentation level. The numbered items are at the least indented level, so the value of w:ilvl is zero. The w:numId element is an index into the w:num elements, which is located in the numbering part.

Note: The w:numId can contain a value of 0, which is a special value that indicates that numbering has been removed at this level of the style hierarchy. While processing this markup, if the w:val='0', the paragraph doesn't have a list item.

The numbering part markup looks like this:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>

<w:numbering xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">

<w:abstractNum w:abstractNumId="0">

<w:nsid w:val="5FE17486"/>

<w:multiLevelType w:val="hybridMultilevel"/>

<w:tmpl w:val="1084E0BA"/>

<w:lvl w:ilvl="0"

w:tplc="0409000F">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:lvlText w:val="%1."/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="720"

w:hanging="360"/>

</w:pPr>

</w:lvl>

<w:lvl w:ilvl="1"

w:tplc="04090019"

w:tentative="1">

<w:start w:val="1"/>

<w:numFmt w:val="lowerLetter"/>

<w:lvlText w:val="%2."/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="1440"

w:hanging="360"/>

</w:pPr>

</w:lvl>

</w:abstractNum>

<w:num w:numId="1">

<w:abstractNumId w:val="0"/>

</w:num>

</w:numbering>

The index in the w:numPr element in the main document part refers to the w:num element highlighted in yellow above. In this case, that element contains a single element, w:abstractNumId, which refers to the w:abstractNum element above it. The w:abstractNum element contains the information necessary to format the list item. Note that the w:abstractNum element does not contain formatting information for the paragraph (except for indentation information, with pertains to both the list item and the paragraph). Formatting for the paragraph itself is stored in the main document and styles part, as usual. There are three elements (w:nsid, w:multiLevelType, and w:tmpl) that only impact the user interface in the word processing application, and you can disregard them. From now on in this post, I will eliminate those elements from markup listings. The w:lvl elements and the w:lvl child elements define the formatting for each indentation level of the list items. There are additional w:lvl elements (removed from the listing) that define the formatting for list items for each level at level two and above. The w:tplc and w:tentative attributes of the w:lvl element are there for the user interface only. I'll remove them from further listings.

Note: the indirection from w:num to w:abstractNum allows for markup that overrides formatting of list items. I'll show this markup later.

The elements that you are really interested in are children of the w:lvl element – the w:start, w:numFmt, w:lvlText, and w:lvlJc elements, and the complex element w:pPr.

The w:start element specifies the starting number for the indentation level. Do you start counting at 0, 1, or some other number? Negative start numbers are not allowed (and are not very useful).

In this example, the w:numFmt element indicates that the document uses a decimal in the list item for indentation level 0, and that the document uses a lower case letter for indentation level 1. There are a fair number of options for this element:

Bullets
Decimal (1, 2, 3)
Decimal Zero (01, 02, 03)
Upper Roman (I, II, III)
Lower Roman (i, ii, iii)
Upper Letter (A, B, C)
Lower Letter (a, b, c)
Ordinal (1st, 2nd, 3rd)
Cardinal Text (One, Two Three)
Ordinal Text (First, Second, Third)

Note: There are other options for other languages that I've not included. Various Asian languages have numbering systems that are not included in this list. In the near future, I'll be posting code to assemble the list item text, and in that code, I am supporting only the above list. I've designed that code so that it is easily extended to include other numbering systems.

You use the w:lvlText element as a template to construct the list item. For level 0, this example uses "%1.", which indicates that whatever w:numFmt text was determined for the least indented item above replaces the %1 in the format string. For level 1, this example uses "%2.", which indicates that whatever text was determined for the first indentation replaces the %2. Note that for the w:lvl elements, you specify indentation level with a zero based index, whereas in the w:lvlText template, you specify replacement tokens using a one based index. This makes sense – the w:lvl elements are used only by developers, and zero based indexes are easier, whereas the template is used and specified by users, so a one based index makes sense. These two elements are pretty powerful, and allow you to put together hierarchical list formats to satisfy just about any need. I will show more examples of these two elements further on.

Note: For bulleted lists, even if the w:lvltext element contains replacement tokens (%1, %2, etc.), the replacement tokens are not replaced with the level number. This does not impact our code, because the w:lvlText element will not contain replacement tokens.

The w:lvlJc element controls whether the list items are right or left justified, as well as some other options. The following shows the difference between left and right justification for numbered items that use text. It is easy to see in this example, but is more difficult to notice when using bulleted lists or numbered lists that use digits.

Finally, there are paragraph properties that apply to the list item, most importantly here specifying the indentation and hanging indentation.

The w:lvl element can also contain run properties that apply to the list item. If you change the font of the list item to Courier, it would look like this:

Her is an example of the w:lvl element that contains run properties that define the font for the list item:

<w:lvl w:ilvl="0">

<w:start w:val="1"/>

<w:numFmt w:val="ordinalText"/>

<w:lvlText w:val="%1)"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="720"

w:hanging="360"/>

</w:pPr>

<w:rPr>

<w:rFonts w:ascii="Courier New"

w:hAnsi="Courier New"

w:hint="default"/>

</w:rPr>

</w:lvl>

As usual, the paragraph in the main document part also contains a reference to a style:

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="0"/>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>One</w:t>

</w:r>

</w:p>

We can find that style in the styles part, which specifies the formatting for the paragraph text:

<w:style w:type="paragraph"

w:styleId="ListParagraph">

<w:name w:val="List Paragraph"/>

<w:basedOn w:val="Normal"/>

<w:pPr>

<w:ind w:left="720"/>

<w:contextualSpacing/>

</w:pPr>

</w:style>

This is the normal pattern for markup for styled paragraphs.

Markup for a Simple Bulleted List

Next, I'll show the markup that is generated if you create a simple bulleted list:

The markup indirection pattern for a simple bulleted list is the same as the pattern for a simple numbering list.

For the simple bulleted list, the main document part (document.xml) contains paragraphs that are identical to the simple numbered list:

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="0"/>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>One</w:t>

</w:r>

</w:p>

Here's what the numbering part looks like:

<w:abstractNum w:abstractNumId="0">

<w:lvl w:ilvl="0">

<w:start w:val="1"/>

<w:numFmt w:val="bullet"/>

<w:lvlText w:val=""/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="720"

w:hanging="360"/>

</w:pPr>

<w:rPr>

<w:rFonts w:ascii="Symbol"

w:hAnsi="Symbol"

w:hint="default"/>

</w:rPr>

</w:lvl>

<w:num w:numId="1">

<w:abstractNumId w:val="0"/>

</w:num>

</w:numbering>

The w:val attribute of the w:lvlText element here is saved as the character 0xB7, which is the bullet symbol for this level (from the Symbol font). The Visual Studio XML editor shows this character as a box in the courier font. The main point about this example is that you can write a generalized method to assemble text for the list item, and this method will work for both numbered and bulleted lists.

The w:start element doesn't have an effect on the list item because the w:lvlText template element doesn't contain a replacement token (%1, %2, etc.) But even if it did, we would not replace the token.

Markup for a Multi-Level List

You can see that this framework nicely allows for multi-level lists. You can change the source document to look like this:

The paragraphs in the main document part looks like this. The w:ilvl element for the second paragraph is set to "1".

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="0"/>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>One</w:t>

</w:r>

</w:p>

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="1"/>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>Two</w:t>

</w:r>

</w:p>

The numbering and style parts are not modified in this example.

Markup for Numbering that is Linked to Styles

There is a feature of numbering that makes it very convenient for users but makes the markup a little more involved. You can link a style to a numbering type and level, and then all paragraphs of that style are then represented with a list item. The canonical example is linking Heading1 style to the first level of indentation, Heading2 style to the second level, and so on. A document using this approach looks like this:

The markup indirection pattern for numbering that is linked to styles looks like this:

In this case, the main document part doesn't contain any markup related to numbering:

<w:p>

<w:pPr>

<w:pStyle w:val="Heading1"/>

</w:pPr>

<w:r>

<w:t>Overview of Numbering</w:t>

</w:r>

</w:p>

<w:p>

<w:pPr>

<w:pStyle w:val="Heading2"/>

</w:pPr>

<w:r>

<w:t>Markup of a Simple Numbered List</w:t>

</w:r>

</w:p>

The markup in the style part for the Heading1 style contains a reference to the w:num element in the numbering part:

<w:style w:type="paragraph"

w:styleId="Heading1">

<w:name w:val="heading 1"/>

<w:basedOn w:val="Normal"/>

<w:pPr>

<w:numPr>

<w:numId w:val="1"/>

</w:numPr>

<w:spacing w:before="480"

w:after="0"/>

<w:outlineLvl w:val="0"/>

</w:pPr>

<w:rPr>

<w:rFonts w:asciiTheme="majorHAnsi"

w:eastAsiaTheme="majorEastAsia"

w:hAnsiTheme="majorHAnsi"

w:cstheme="majorBidi"/>

<w:b/>

<w:bCs/>

<w:color w:val="365F91"

w:themeColor="accent1"

w:themeShade="BF"/>

<w:sz w:val="28"/>

<w:szCs w:val="28"/>

</w:rPr>

</w:style>

The numbering part looks like this:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>

<w:numbering xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">

<w:abstractNum w:abstractNumId="0">

<w:lvl w:ilvl="0">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:pStyle w:val="Heading1"/>

<w:lvlText w:val="%1"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="432"

w:hanging="432"/>

</w:pPr>

</w:lvl>

<w:lvl w:ilvl="1">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:pStyle w:val="Heading2"/>

<w:lvlText w:val="%1.%2"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="576"

w:hanging="576"/>

</w:pPr>

</w:lvl>

</w:abstractNum>

<w:num w:numId="1">

<w:abstractNumId w:val="0"/>

</w:num>

</w:numbering>

The w:pStyle element links back to the style in the style part. You determine the indentation level by finding the w:pStyle element that matches the style of the paragraph and looking at the parent w:lvl complex element. As usual, you assemble the text of the list item from the other child elements of the w:lvl element.

Overriding a Number Format in a Multi-Level List with a New Number Format

You can override the numbering format for any level in a multi-level list with a new number format, and this impacts the markup. To create this markup, first create a multi-level list:

Then select a paragraph, and define a new number format:

In the Define new Number Format dialog box, change some aspect. In this example, I changed Heading2 so that the list item is the cardinal number followed by a parenthesis: "One)".

The markup for the main document part now looks like this:

<w:p>

<w:pPr>

<w:pStyle w:val="Heading1"/>

</w:pPr>

<w:r>

<w:t>Paragraph One</w:t>

</w:r>

</w:p>

<w:p>

<w:pPr>

<w:pStyle w:val="Heading2"/>

<w:numPr>

<w:ilvl w:val="1"/>

<w:numId w:val="2"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>Paragraph Two</w:t>

</w:r>

</w:p>

<w:p>

<w:pPr>

<w:pStyle w:val="Heading3"/>

</w:pPr>

<w:r>

<w:t>Paragraph Three</w:t>

</w:r>

</w:p>

The markup in the numbering part now has two w:num elements, each pointing to their own abstract numbering format:

<w:num w:numId="1">

<w:abstractNumId w:val="1"/>

</w:num>

<w:num w:numId="2">

<w:abstractNumId w:val="0"/>

</w:num>

The abstract numbering markup can be then processed as usual. The main point here is when you format numbering using styles, the markup follows the indirection detailed in this section, but if a paragraph of that style contains a w:numPr element, this overrides the link from the abstract numbering format to the style.

Overriding a Number Format in a Multi-Level List, creating a new Multi-Level List Format

The user can override the numbering format for any level in a multi-level list, creating a new multi-level list format, and this impacts the markup. To create this markup, first create a multi-level list:

Then select a paragraph, and define a new multi-level list:

In the Define new Multilevel list dialog box, change some aspect of the list level. In my example, I changed the format so that list items at the second level of indentation use upper case alpha for the item marker.

The markup for the main document part contains a w:numPr element that overrides the link from the abstract numbering format to the style, in the same way as when creating a new number format:

<w:p>

<w:pPr>

<w:pStyle w:val="Heading1"/>

</w:pPr>

<w:r>

<w:t>Paragraph One</w:t>

</w:r>

</w:p>

<w:p>

<w:pPr>

<w:pStyle w:val="Heading2"/>

<w:numPr>

<w:ilvl w:val="1"/>

<w:numId w:val="3"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>Paragraph Two</w:t>

</w:r>

</w:p>

<w:p>

<w:pPr>

<w:pStyle w:val="Heading3"/>

</w:pPr>

<w:r>

<w:t>Paragraph Three</w:t>

</w:r>

</w:p>

The w:numPr element in the paragraph properties overrides the link between the abstract numbering format and the Heading2 style. The numbering part now contains a new w:num element that defines w:lvlOverride elements:

<w:num w:numId="1">

<w:abstractNumId w:val="0"/>

</w:num>

<w:num w:numId="2">

<w:abstractNumId w:val="1"/>

</w:num>

<w:num w:numId="3">

<w:abstractNumId w:val="0"/>

<w:lvlOverride w:ilvl="0">

<w:lvl w:ilvl="0">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:pStyle w:val="Heading1"/>

<w:lvlText w:val="%1"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="432"

w:hanging="432"/>

</w:pPr>

<w:rPr>

<w:rFonts w:hint="default"/>

</w:rPr>

</w:lvl>

</w:lvlOverride>

<w:lvlOverride w:ilvl="1">

<w:lvl w:ilvl="1">

<w:start w:val="1"/>

<w:numFmt w:val="upperLetter"/>

<w:pStyle w:val="Heading2"/>

<w:lvlText w:val="%1.%2"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="576"

w:hanging="576"/>

</w:pPr>

<w:rPr>

<w:rFonts w:hint="default"/>

</w:rPr>

</w:lvl>

</w:lvlOverride>

. . .

Two of the w:num elements now refer to the same abstract numbering format, but the second one now overrides the list item formatting. You can see that the level override for level 1 now specifies that the value for the w:numFmt element is "upperLetter".

The w:startOverride Element

The w:lvlOverride element can contain a child w:startOverride element:

<w:num w:numId="2">

<w:abstractNumId w:val="2"/>

<w:lvlOverride w:ilvl="0">

<w:startOverride w:val="5"/>

</w:lvlOverride>

<w:lvlOverride w:ilvl="1">

<w:startOverride w:val="1"/>

</w:lvlOverride>

. . .

</w:num>

The w:startOverride element causes the starting number of the indent level to be the value specified. This is sometimes used when the user specifically sets this value in the user interface to force counting to start from a specific number. This is one way that markup forms a document that skips an number in a numbered list:

There is another way that markup can specify a starting number. I'll show this markup this shortly.

Defining a new List Style

One option in Word is that you can define a new named list style, and then use that style elsewhere in the document. This is a quick and easy way to implement your own customized numbering format. To do this, select the text to number, and pick "Define New List Style" from the Multi-level List drop down:

This brings up the Define New List Style dialog box.

After filling out this dialog, the selected paragraphs will have the numbering format that you specify. You can then further apply this same style in other locations in the document. Using this feature impacts the markup.

Here is the indirection when using this pattern:

The document part looks the same as when applying other forms of numbering:

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="0"/>

<w:numId w:val="2"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>1</w:t>

</w:r>

</w:p>

We can find the referenced w:num element in the numbering part:

<w:num w:numId="2">

<w:abstractNumId w:val="0"/>

</w:num>

But if we look at the abstract numbering element, it looks quite different. It doesn't contain child w:lvl elements, and uses the w:numStyleLink element to refer to the style that I defined in the dialog box.

<w:abstractNum w:abstractNumId="0">

<w:nsid w:val="03916EF0"/>

<w:multiLevelType w:val="multilevel"/>

<w:tmpl w:val="0409001D"/>

<w:numStyleLink w:val="EricsListStyle"/>

</w:abstractNum>

In the styles part, you can find the newly defined style, which then refers back to a w:num element in the numbering part:

<w:style w:type="numbering"

w:customStyle="1"

w:styleId="EricsListStyle">

<w:name w:val="EricsListStyle"/>

<w:uiPriority w:val="99"/>

<w:rsid w:val="00B1427D"/>

<w:pPr>

<w:numPr>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

</w:style>

The w:num element in the numbering part looks like this:

<w:num w:numId="1">

<w:abstractNumId w:val="1"/>

</w:num>

This refers to a w:abstractNum element, which contains the level formats, as usual:

<w:abstractNum w:abstractNumId="1">

<w:nsid w:val="2D235466"/>

<w:multiLevelType w:val="multilevel"/>

<w:tmpl w:val="0409001D"/>

<w:styleLink w:val="EricsListStyle"/>

<w:lvl w:ilvl="0">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:lvlText w:val="%1)"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="360"

w:hanging="360"/>

</w:pPr>

</w:lvl>

<w:lvl w:ilvl="1">

<w:start w:val="1"/>

<w:numFmt w:val="lowerLetter"/>

<w:lvlText w:val="%2)"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="720"

w:hanging="360"/>

</w:pPr>

</w:lvl>

. . .

This is a fair amount of indirection, but using LINQ to XML, it results in only a few statements to follow this indirection.

Alternatives for the List Item Suffix

The list suffix is the white space content between the list item and the paragraph. There are only two possible values – tab and space. We can alter a list definition to use a space for the list item suffix instead of a tab:

The markup uses the w:suff element to specify this:

<w:abstractNum w:abstractNumId="0">

<w:nsid w:val="21E167DA"/>

<w:multiLevelType w:val="multilevel"/>

<w:tmpl w:val="5BE82C98"/>

<w:lvl w:ilvl="0">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:pStyle w:val="Heading1"/>

<w:suff w:val="space"/>

<w:lvlText w:val="%1"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="432"

w:hanging="432"/>

</w:pPr>

<w:rPr>

<w:rFonts w:hint="default"/>

</w:rPr>

</w:lvl>

The w:lvlRestart Element

The w:lvlRestart element allows the markup to control when a particular level restarts counting. In the following example, the level four list item starts recounting when there is an intervening level one item:

The markup (for the above example) for the w:lvl element where the w:ilvl attribute is equal to "3" looks like this:

<w:abstractNum w:abstractNumId="0">

<w:nsid w:val="065A6A4E"/>

<w:multiLevelType w:val="multilevel"/>

<w:tmpl w:val="06A2CF44"/>

<w:lvl w:ilvl="3">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:lvlRestart w:val="1"/>

<w:lvlText w:val="%1.%2.%3.%4."/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="1728"

w:hanging="648"/>

</w:pPr>

<w:rPr>

<w:rFonts w:hint="default"/>

</w:rPr>

</w:lvl>

The w:isLgl Element

The w:isLgl element changes the textual representation of a list item so that it uses digits for all levels instead of the specified number format for that level, but only when formatting text for a given indentation level. Consider the following document, where items at the third indentation level use legal numbering:

If this list didn't use legal numbering for the third level of indentation, it would look like this:

The markup for w:isLgl looks like this:

<w:abstractNum w:abstractNumId="0">

. . .

<w:lvl w:ilvl="2">

<w:start w:val="1"/>

<w:numFmt w:val="decimal"/>

<w:pStyle w:val="Heading3"/>

<w:isLgl/>

<w:lvlText w:val="%1.%2.%3)"/>

<w:lvlJc w:val="left"/>

<w:pPr>

<w:ind w:left="720"

w:hanging="720"/>

</w:pPr>

<w:rPr>

<w:rFonts w:hint="default"/>

</w:rPr>

</w:lvl>

Algorithm to Assemble List Item Text

The key aspects for assembling list item text is to determine:

The w:lvl formatting for the paragraph
The indentation level of the paragraph
The number for each parent level of indentation for the paragraph. For example, if a paragraph is at the 4th indentation level, you need to determine the level numbers of the 1st, 2nd, 3rd, and 4th levels associated with that paragraph.

Once you have these three items, it is a simple text formatting exercise to assemble the list item text.

A paragraph may contain numbering properties that contain a w:ilvl and w:numId element.

<w:p>

<w:pPr>

<w:pStyle w:val="ListParagraph"/>

<w:numPr>

<w:ilvl w:val="0"/>

<w:numId w:val="1"/>

</w:numPr>

</w:pPr>

<w:r>

<w:t>Paragraph one.</w:t>

</w:r>

</w:p>

In this case, you use the w:ilvl specified for the indentation level. You go to the numbering part, and look up the w:num element. If there is a w:lvlOverride element that contains a w:lvl element, then that w:lvl element applies. If there is no w:lvlOverride element, or if the w:lvlOverride element doesn’t contain a w:lvl element for the indentation level, then find the associated w:abstractNum element, and use the w:lvl formatting specified in the w:abstractNum. If the w:num element contains a w:lvlOverride element, you use the w:lvl specified for the indentation level in the override.

If the paragraph does not contain a w:numPr complex element, then if the style of the paragraph contains a w:numPr element, there is an abstract numbering element that refers to the style. We use the w:lvl that refers to the style. This also gives us the indentation level.

Once we've determined the w:lvl formatting element, and the indentation level, we can determine the list number for each level. You need to count the paragraphs at the same level before the current paragraph, paying attention to the w:lvlRestart element and the w:start element. This is where functional programming will shine – I can build a stateless expression to calculate the item number for each indentation level. This may not be the most efficient way to do this – it may use more CPU processing than another approach, but it will be easy to debug, and probably fast enough for most scenarios. In my informal testing on my slowest machine, it is still basically instantaneous.

Once you have the appropriate w:lvl element and the list of item numbers for each level of indentation, it is a simple text assembly process to put together the list item text.

This may seem like a lot of logic to assemble the list item text, but it is less than 400 lines of code when properly factored and implemented using LINQ to XML.

Eric White's Blog : LINQ to XML

Working with Numbering in Open XML WordprocessingML

Markup for a Simple Numbered List

Markup for a Simple Bulleted List

Markup for a Multi-Level List

Markup for Numbering that is Linked to Styles

Overriding a Number Format in a Multi-Level List with a New Number Format

Overriding a Number Format in a Multi-Level List, creating a new Multi-Level List Format

The w:startOverride Element

Defining a new List Style

Alternatives for the List Item Suffix

The w:lvlRestart Element

The w:isLgl Element

Algorithm to Assemble List Item Text