DTD Attribute Types - ID

• Type: Enumerated
• Type: IDREF

The attribute type of ID is used specifically to identify elements.

Because of this, no two elements can contain the same value for attributes of type ID. Also, you can only give an element one attribute of type ID. The value that is assigned to an attribute of type ID must be a valid XML name.

Syntax:

Example:

Valid XML - The following XML document would be valid, as it conforms to the above DTD:

Invalid XML - The following XML document would be invalid because the value of the mountain_id attribute is the same for both elements:

• Type: Enumerated
• Type: IDREF