Ol

Ordered List Support Key: [2\|3\|3.2\|4] [X1\|X1.1] [IE1\|M1\|N1\|O2.1]	What is it? Attributes Tag Example	Parent/Content Model Tips & Tricks Browser Peculiarities
= Index DOT Html by Brian Wilson =

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Quick Statistics
End Tag:		Required
Standards Details:		HTML: In all 4.x DTDs XHTML: In all 1.0 and 1.1 DTDs
XHTML Modules:		List
CSS 'display' Type:		"block"
CSS Mapping:		NA
Default Rendering:		Block element with left margin. Each LI element has a number prefix before it.
Official Docs:		HTML 4.x, XHTML 1.1

What is it?: The Ordered List element represents a list of items sorted by sequence or order of importance. Typical rendering is a numbered list of items. The only content of this list structure is the <li> (list item) element. As with other list types, the closing </li> tag is optional in HTML (Required in XHTML), as it is implied by the subsequent <li> or end </ol> tags.

Common Attributes
%Core%: [2|3|3.2|4] [X1|X1.1] [IE3|M|N4B2|O3.5]
%Accessibility%: [2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6|O5]
%Events%: [2|3|3.2|4] [X1|X1.1] [IE4B1|M|N6B1|O4]
%Language%: [2|3|3.2|4] [X1|X1.1] [IE4|M|N6B1|O]
%Editing%: [2|3|3.2|4] [X1|X1.1] [IE5.5|M|N|O]
Specific Attributes
Align
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O4]: Standards Details: NA; Required? No; Description:
This indicates the horizontal alignment of the content in this block element relative to the browser window.; Values: Left [DEFAULT] | Center | Right
Clear
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O2.1-6.x]: Standards Details: NA; Required? No; Description:
This attribute helps an author in situations with floating objects (images, tables, etc.) produced through the Left and Right ALIGN attributes. It allows content to stop being flowed around the floated element.; Values:
   None [DEFAULT - No special line breaking effects are applied relative to the floating element.]
   Left [breaks line after this element and moves down vertically until the left margin is clear of floated objects.]
   Right [breaks line after this element and moves down vertically until the right margin is clear of floated objects.]
   All [breaks line after this element and moves down vertically until both margins are clear of floated objects.]
Compact
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]: Standards Details: Deprecated in HTML 4.x/XHTML 1.0; Not present in XHTML 1.1; Required? No; Description:
This is a stand alone attribute flag that indicates a compact rendering be used if possible, possibly because the list items are small or the entire list is large.; Values: NA (HTML); compact (XHTML)
Height
[2|3|3.2|4] [X1|X1.1] [IE|M| N |O4-6.x]: Standards Details: NA; Required? No; Description:
This attribute explicitly specifies the height of this block element in pixels.; Values: Positive integers.
SDAForm
[2|3|3.2|4] [X1|X1.1] [IE|M|N|O]: Standards Details: NA; Required? No; Description:
This is an SGML Document Access (SDA) attribute. SDA attributes are designed to transform HTML (and other SGML-based documents) to the ICADD DTD - which is used in creating accessible documents for users with visual disabilities (rendering in Braille, large print, speech synthesis, etc.) The attribute value specifies the name of the element to convert this element to in the SDA element group (in this case the 'List' element - "list of items".); Value: List (Denotes a 'list of items' in SDA.)
Start
[2|3|3.2|4] [X1|X1.1] [IE4|M|N1|O2.1]: Standards Details: Deprecated in HTML 4.x/XHTML 1.0; Not present in XHTML 1.1; Required? No; Description:
This attribute specifies the number to be used for the first item in the list. Subsequent list items by default will count upwards from this initial value (default is "1".) The value is specified using decimal notation. Negative numbers and zero are permitted by the HTML/XHTML specifications, but some browsers do not support them. The rendering of numbers for list markers is also usually affected by the TYPE attribute, if present. If ordered list TYPE values are specified ("a", "A", "i", "I", and "decimal") then the START attribute will be honored, with the numbering mapped to the TYPE being used. If unordered list TYPE values are specified ("disc", "square", "circle", "round"), then the START attribute will be ignored.; Values: Specified as integers. Default value is "1"
Type
[2|3|3.2|4] [X1|X1.1] [IE4|M|N1|O2.1]: Standards Details: Deprecated in HTML 4.x/XHTML 1.0; Not present in XHTML 1.1; Required? No; Description:
The TYPE attribute indicates different ordering label schemes to be used instead of the default 1, 2, 3, etc.; Values:
   none [no marker is used]
   A [capital letters]
   a [lower-case letters]
   I [large roman numerals]
   i [small roman numerals]
   upper-alpha [capital letters]
   lower-alpha [lower-case letters]
   upper-roman [large roman numerals]
   lower-roman [small roman numerals]
   decimal [integer numbering - DEFAULT]
   disc [default solid bullet]
   square [solid square]
   circle [hollow bullet]
   round [hollow bullet]
Width
[2|3|3.2|4] [X1|X1.1] [IE|M| N |O4-6.x]: Standards Details: NA; Required? No; Description:
This attribute explicitly specifies the width of this block element in pixels.; Values: Positive integers.

Example: <ol type="A" start="3">
   <li>List item 1</li>
   <li>List item 2</li>
   <li>List item 3</li>
</ol>

Parent Model: %Block Parent%
Content Model: <li>

Tips & Tricks

Some people leverage on a behavioral defect in browsers whereby embedding data in a list structure without LI elements will induce indentation. Strictly speaking, this HTML is not valid with respect to the established standards. Even using an HTML 3.0 element like the "List Header" (LH) at the beginning of a list structure would produce this effect, but this syntax has never been a part of an accepted standard. Such syntax is illegal in current HTML/XHTML standards and not recommended. Other methods can be used to enforce indentation that are much safer.
Changing the font attributes (size, color, etc.) of the contents of a List Item will not affect the appearance of the listing mechanism (bullets.)
Lists are nestable.

Browser Peculiarities

[Test] Internet Explorer, Mosaic, Netscape and Opera all produce the above described indenting behavior for the mentioned invalid HTML.
[Test] Both Internet Explorer and Netscape alter the listing mechanism (the bullets) if a font changing tag (e.g. FONT SIZE) spans a list structure or if it is placed incorrectly before the first LI tag.
Internet Explorer 4.0 does not know how to properly count roman numerals - all versions of 900-999 (also 1900-1999, 2900-2999, etc.) use "CW" where they should instead use "CM". Later Internet Explorer versions are fine (thanks to Chris Findlay who alerted me to this whole roman numeral pile of worms.)

[Test] It seems that ALL browsers have problems with roman numeral lists. The two big problems are list marker rendering and numbers greater than 3999 (roman numeral counting changes at 4000 from the normal pattern.)
Roman Numeral List Rendering Problems:

Browser	Version	What happens at 4000?	List marker rendering
Internet Explorer	3	Displays as integer numerals where: 3999=correct roman, 4000="1", 4001="2", etc.	Ok
	4-5.5	Displays as integer numerals where: 3999=correct roman, 4000="1", 4001="2", etc.	Markers too large overlap onto content.
Netscape	1	Restarts at 4000 in roman numerals off by 2, where: 3999=correct roman, 4000="ii", 4001="iii"	Content masks the marker, but marker can reappear if content is too short or marker is too long.
	1.2-4.x	Displays as integer numerals where: 3999=correct roman, 4000="1", 4001="2", etc.	Markers too large overlap onto content.
	6.x	Restarts at 4000 in error mode, where: 3999=correct roman, 4000="m?", 4001="m?i"	Markers too large extend into left page margin
Opera	3.2	Displays correctly up to 3999, and "....." for all markers >=4000	Ok
	3.5-3.6x	Displays correctly up to 3999, and "....." for all markers >=4000	Markers too large overlap onto content.
	4.0	Displays correctly up to 3999, and "....." for all markers >=4000	Markers too large extend into left page margin

One last thing about roman numeral counting: Opera display was often problematic - often breaking the content or marker alignment, and dropping counting a marker (one O3.2 case failed at 94 out of 1100, and O3.5 messed up #3364 out of 4100 items.) This seems fairly trivial, but it also messed up when the START attribute is set, which exposes problems with higher numbers much sooner.
[Test] START attribute behavior for "0" and negative values:
IE: (all) Both value types honored
Netscape/Mozilla: (all) Ignored
Opera 2.1-6.x: Ignored
Opera 7.x+: "0" honored, negative values causes all list markers for the list to go away.

Ordered List