They may appear in any order. Attribute names are always case-insensitive.
Attribute values are generally case-insensitive.
A single character is used as the value of this attribute. A single, case-insensitive alphanumeric character from a browser's character set. The value of an ID attribute belonging to a form field in the current document. In addition to the specific attributes above, there are more generic attributes which have been organized into three separate categories. Trigger external or inline script code.