HTML Quick Reference - HTML5 and CSS Comprehensive - page 699

Table H-16 General Form of an Element Declaration

General form: <!ELEMENT element-name (rule)>

Comment: !ELEMENT is the declaration; element-name is any valid XML element name (see rules in Table

H-3 on page APP 74); rule is a keyword, such as ANY or #PCDATA. The ANY keyword means
other valid tags and data can be displayed; #PCDATA means only parsed character data can be
displayed.

Example: <!ELEMENT SONG (Title, Singer)>

<!ELEMENT Title (#PCDATA)>
<!ELEMENT Singer (#PCDATA)>

Attribute List Declarations
A DTD can also contain an attribute list declaration. The items in the attribute list
must correspond to any attributes declared within XML elements. Table H-17 shows the
general form of an attribute list declaration.

Table H-17 General Form of an Attribute List Declaration

General form: <!ATTLIST element-name attribute-name data-type default-value>

Comment: The element-name is the name of the XML element. The attribute-name is the name of the

attribute. The data-type is the data type of the attribute. The default-value is any default value
of the attribute. In the example, width is an attribute of the txtBox element, with a CDATA
(character data) type and default value of 10.

Example: <!ATTLIST txtBox width CDATA "10">

The data type in an attribute list declaration can be one of 10 different kinds of data type
attributes, as shown in Table H-18.

Table H-18 DTD Data Type Attributes

Type Description

CDATA Character data; can include any character string as well as special symbols for ampersand (&amp),

less-than and greater-than symbols or angle brackets (&lt or &gt), or quotation marks (&quot)

Enumerated List of possible values for an attribute (such as cash/check/charge); only one can be used

ENTITY Single entity; either external data or declared DTD entity

ENTITIES Multiple entities; either external data or declared in DTD

ID Unique element identifier for an attribute that distinguishes one element from others

IDREF Identifies the value of a unique ID of another element

IDREFS Identifies multiple values for an attribute, separated by white space

NMTOKEN XML name token; restricts the attribute value to any valid XML name (letters, number,

hyphens, underscores, and periods)

NMTOKENS Allows the attribute value to include multiple XML names, separated by white space

NOTATION Allows the attribute value to be a value specified in a DTD notation declaration

The default value in an attribute list declaration must match the data type. If a specific
value is noted, the value must be enclosed within quotation marks. A default value consists
of one of the four options shown in Table H-19.