Disable a group of related form elements:
The disabled attribute is a boolean attribute.
When present, it specifies that a group of related form elements (a fieldset) should be disabled.
A disabled fieldset is unusable and un-clickable.
Note: In Internet Explorer, this attribute will change the color of the form elements to gray, but they will still be usable (not disabled).
The numbers in the table specify the first browser version that fully supports the attribute.
The disabled attribute is new for the <fieldset> tag in HTML5.
In XHTML, attribute minimization is forbidden, and the disabled attribute must be defined as <fieldset disabled="disabled">.