Element Descriptions

For each of the elements in the dtbk3-03.dtd in the order they occur in the DTD the following information is supplied:

1. <Element name>
2. Description, with suffix if from [HTML 4.0]
3. Contains: original element type declaration, and Expanded: if original has any parameter entities in its content model.
4. Occurs within: list of element names in which this element may (or must) occur directly, in their content models.
5. Attributes: Original: and Expanded: if there are parameter entities they are expanded.

Element Declarations are shown as:

<!ELEMENT elementname

Contains:
	EMPTY or original content model:
Expanded:
	content model with parameter entities expanded

>

EMPTY declared content denotes that the element has no explicit content. Instead its purpose is to mark a position, and to associate attribute values to that position. The XML-approved way to indicate the end-tag of such an element is by the special tag close ' />'. That leading space (after the end of the final quoted value for an attribute) is presumed by some browsers.

For example, using the EMPTY horizontal irule tag:

<hr title="horizontal rule purpose" />

or for backward compatibility the more common end tag form may be used:

< hr title="horizontal rule purpose"></hr>

Element content models are formed from a parenthesized list of names of other elements or parameter entities of the form %name; or #PCDATA, separated by connectors:

Connector	Use	Example
,	sequence	(x,y) is x followed by y
|	alternative	(x|y) is either x or y
(...)	grouping	(x,(y|z)) is x followed by either y or z

Individual names or groupings of them may have a following replicator (by default no replicator means one of:

Replicator	Use	Example
?	optional	x? means zero or one of x
*	optional and repeatable	x* means zero or more of x
+	Repeatable	x+ means one or more of x
none	One only	x means just one x

#PCDATA is a special name allowing text. The only place that it can occur in a content model is first among alternatives:

(#PCDATA | x | y)+

means choose among one or more of x or y intermixed with text.

#PCDATA stands for "parsed character data", indicating that the content may include entities representing non-ASCII characters, intermixed with the ASCII characters. The form for referencing such entities is

&xHHHH;

where the HHHH denotes a Unicode hexidecimal code position.

Attribute List Declarations have one or more attributes. Each attribute has three parts: Name, Declared Value, and Default Value. They are shown as:

1. Name of attribute as it may appear in a document tag,in the form: name="value".
2. Declared value of attribute, of various types:

   Attribute Type	Explanation
   ID	identifier, formed from letters (case sensitive), digits, dash, underscore, and period.
   IDREF	Value is one ID value
   IDREFS	Values are one or more space-separated ID values
   CDATA	character string, with the semantic meaning suggested by the parameter entity name.
   (name1|name2|...)	Select at most one among the alternatives

3. Default value of attribute, of various kinds:

   Default Value	Explanation
   #IMPLIED	attribute and its value may be omitted, and if so, the meaning is up to the system.
   #REQUIRED	attribute and its value must be included.
   quoted value	One of the explicit names in the Declared value.

Hyperlinking:

• Each element name in the <!Element elementname Contains: ... and Expanded: ... > is linked to its description.
• Each parameter entity reference (%name;) in the Element and Attribute list is linked to the corresponding entry in the Parameter Entities Sorted section. Since they are expanded where they occur, the parameter entity reference links need not usually be followed.