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7.3. The <li> Tag

It should be quite obvious to you by now that the <li> tag defines an item in a list. It's the universal tag for list items in ordered (<ol>) and unordered (<ul>) lists, as we discussed earlier, and for directories (<dir>) and menus (<menu>), which we discuss in detail later in this chapter.

<li>

Function:

Define an item within an ordered, unordered, directory, or menu list

Attributes:

CLASS

ONMOUSEDOWN

DIR

ONMOUSEMOVE

ID

ONMOUSEOUT

LANG

ONMOUSEOVER

ONCLICK

ONMOUSEUP

ONDBLCLICK

STYLE

ONKEYDOWN

TITLE

ONKEYPRESS

TYPE

ONKEYUP

VALUE

End tag:

</li>; often omitted in HTML

Contains:

flow

Used in:

list_content

Because the end of a list element can always be inferred by the surrounding document structure, most authors omit the ending </li> tags for their list elements. That makes sense because it becomes easier to add, delete, and move elements around within a list. However, XHTML requires the end tag, so it's best to get used to including it in your documents.

Although universal in meaning, there are some differences and restrictions to the use of the <li> tag for each list type. In unordered and ordered lists, what follows the <li> tag may be nearly anything, including other lists and multiple paragraphs. Typically, if it handles indentation at all, the browser successively indents nested list items, and the content in those items is justified to the innermost indented margin.

Directory and menu lists are another matter. They are lists of short items like a single word or simple text blurb and nothing else. Consequently, <li> items within <dir> and <menu> tags may not contain other lists or other block elements, including paragraphs, preformatted blocks, or forms.

Clean documents, fully compliant with the HTML and XHTML standards, should not contain any text or other document item inside the unordered, ordered, directory, or menu lists that is not contained within an <li> tag. Most browsers are tolerant of violations to this rule, but then you can't hold the browser responsible for compliant rendering for exceptional cases, either.

7.3.1. Changing the Style and Sequence of Individual List Items

Just as you can change the bullet or numbering style for all of the items in an unordered or ordered list, you also can change the style for individual items within those lists. With ordered lists, you also can change the value of the item number. As you'll see, the combinations of changing style and numbering can lead to a variety of useful list structures, particularly when included with nested lists. Do note, however, that the standards have deprecated these attributes in deference to their CSS counterparts.

7.3.1.1. The type attribute

Acceptable values for the type attribute in the <li> tag are the same as the values for the appropriate list type: items within unordered lists may have their type set to circle, square, or disc, while items in an ordered list may have their type set to any of the values shown previously in Table 7-1.

Careful. With earlier browsers, such as Netscape Navigator and Internet Explorer versions 4 and earlier, a change in the bullet or numbering type in one list item similarly affected subsequent items in the list. Not so for HTML 4-compliant browsers, such as Netscape version 6 and Internet Explorer version 5! The type attribute effects are acute and limited to only the current <li> tag. Subsequent items revert to the default type; each must contain the specified type.

Figure 7-4 shows the effect changing the type for an individual item in an ordered list has on subsequent items, as rendered by Internet Explorer from the following source:

<ol>
  <li type=A>Changing the numbering type</li>
  <li type=I>Uppercase Roman numerals</li>
  <li type=i>Lowercase Roman numerals</li>
  <li type=1>Plain ol' numbers</li>
  <li type=a>Doesn't alter the order.</li> 
  <li> &lt;-- But, although numbering continues sequentially,</li>
  <li> types don't persist. See? I should've been a "g"!</li>
</ol>
Figure 7-4

Figure 7-4. Changing the numbering style for each item in an ordered list

type changes the display style of the number, but not the value of the number.

You may use the style sheet-related style and class attributes to effect individual type changes in ordered and unordered lists that may or may not affect subsequent list items. Please see Chapter 8, "Cascading Style Sheets" for details, particularly Section 8.4.7.5, "Using list properties effectively".



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