About
Attribute in XML represents the (tree) attributes of an HTML element (node in the tree)
Ie they are used to associate name-value pairs with elements and are defined in a start tag of an empty tag.
The Name-Value pairs are referred to as the attribute specifications of the element.
In HTML, they are characteristics or descriptions for the content in the element.
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Example
<termdef id="dt-dog" term="dog">
This Xml start tag defines:
- for the attribute name “id” the attribute value “dt-dog”
- for the attribute name “term” the attribute value “dog”
HTML Specification: The attribute value can remain unquoted if it doesn't contain space characters or any of “ ' ` = < or >. Otherwise, it has to be quoted using either single or double quotes. The value, along with the ”=“ character, can be omitted altogether if the value is the empty string.
<!-- empty attributes -->
<input name=address disabled>
<input name=address disabled="">
<!-- attributes with a value -->
<input name=address maxlength=200>
<input name=address maxlength='200'>
<input name=address maxlength="200">
List
All the attributes of an element are called the attribute list.
The list of supported attribute for an element can be defined in the attribute-list declaration
Declaration
An Attribute-list declaration is a declaration that specify the list of possible attribute for an element.
See attribute-list declaration for an example.