built-in data type
The specified-attribute type is one of two subtypes of declared-attribute. All items of the
specified attributes shelf have this type, and so does any item of the attributes shelf that
corresponds to a specified or defaulted attribute.
Every specified-attribute has two properties: its declaration and its string value, which is always valid against the declaration.
The value of a specified-attribute instance can be obtained simply by using the instance as a string. The opposite conversion can also be performed, because any string value can be cast to a
specified-attribute. The attribute-declaration of the specified-attribute obtained in
this way will accept any string value, corresponding to a CDATA #IMPLIED
declaration in SGML or XML.
Operator create-specified-attribute can be used to create a new instance of the type without the
use of a parser, and a shelf of specified attributes can be passed to create-element-event to create a
new element event with these attributes.