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XPath Introduction XPath Nodes XPath Syntax XPath Axes XPath Operators XPath Examples

XSLT Tutorial

XSLT Introduction XSL Languages XSLT Transform XSLT <template> XSLT <value-of> XSLT <for-each> XSLT <sort> XSLT <if> XSLT <choose> XSLT Apply XSLT on the Client XSLT on the Server XSLT Edit XML XSLT Examples

XQuery Tutorial

XQuery Introduction XQuery Example XQuery FLWOR XQuery HTML XQuery Terms XQuery Syntax XQuery Add XQuery Select XQuery Functions

XML DTD

DTD Introduction DTD Building Blocks DTD Elements DTD Attributes DTD Elements vs Attr DTD Entities DTD Examples

XSD Schema

XSD Introduction XSD How To XSD <schema> XSD Elements XSD Attributes XSD Restrictions

XSD Complex

XSD Elements XSD Empty XSD Elements Only XSD Text Only XSD Mixed XSD Indicators XSD <any> XSD <anyAttribute> XSD Substitution XSD Example

XSD Data

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Web Services

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References

DOM Node Types DOM Node DOM NodeList DOM NamedNodeMap DOM Document DOM Element DOM Attribute DOM Text DOM CDATA DOM Comment DOM XMLHttpRequest DOM Parser XSLT Elements XSLT/XPath Functions

DTD - Attributes


In a DTD, attributes are declared with an ATTLIST declaration.


Declaring Attributes

An attribute declaration has the following syntax:

<!ATTLIST element-name attribute-name attribute-type attribute-value>

DTD example:

<!ATTLIST payment type CDATA "check">

XML example:

<payment type="check" />

The attribute-type can be one of the following:

Type Description
CDATA The value is character data
(en1|en2|..) The value must be one from an enumerated list
ID The value is a unique id
IDREF The value is the id of another element
IDREFS The value is a list of other ids
NMTOKEN The value is a valid XML name
NMTOKENS The value is a list of valid XML names
ENTITY The value is an entity
ENTITIES The value is a list of entities
NOTATION The value is a name of a notation
xml: The value is a predefined xml value

The attribute-value can be one of the following:

Value Explanation
value The default value of the attribute
#REQUIRED The attribute is required
#IMPLIED The attribute is optional
#FIXED value The attribute value is fixed

A Default Attribute Value

DTD:
<!ELEMENT square EMPTY>
<!ATTLIST square width CDATA "0">

Valid XML:
<square width="100" />

In the example above, the "square" element is defined to be an empty element with a "width" attribute of  type CDATA. If no width is specified, it has a default value of 0.


#REQUIRED

Syntax

<!ATTLIST element-name attribute-name attribute-type #REQUIRED>

Example

DTD:
<!ATTLIST person number CDATA #REQUIRED>

Valid XML:
<person number="5677" />

Invalid XML:
<person />

Use the #REQUIRED keyword if you don't have an option for a default value, but still want to force the attribute to be present.


#IMPLIED

Syntax

<!ATTLIST element-name attribute-name attribute-type #IMPLIED>

Example

DTD:
<!ATTLIST contact fax CDATA #IMPLIED>

Valid XML:
<contact fax="555-667788" />

Valid XML:
<contact />

Use the #IMPLIED keyword if you don't want to force the author to include an attribute, and you don't have an option for a default value.


#FIXED

Syntax

<!ATTLIST element-name attribute-name attribute-type #FIXED "value">

Example

DTD:
<!ATTLIST sender company CDATA #FIXED "Microsoft">

Valid XML:
<sender company="Microsoft" />

Invalid XML:
<sender company="learningslack" />

Use the #FIXED keyword when you want an attribute to have a fixed value without allowing the author to change it. If an author includes another value, the XML parser will return an error.


Enumerated Attribute Values

Syntax

<!ATTLIST element-name attribute-name (en1|en2|..) default-value>

Example

DTD:
<!ATTLIST payment type (check|cash) "cash">

XML example:
<payment type="check" />
or
<payment type="cash" />

Use enumerated attribute values when you want the attribute value to be one of a fixed set of legal values.